diff --git a/swad_account.c b/swad_account.c
index 91ac89fd4..d5ff22b74 100644
--- a/swad_account.c
+++ b/swad_account.c
@@ -736,7 +736,7 @@ void Acc_CreateNewUsr (struct UsrData *UsrDat,bool CreatingMyOwnAccount)
    char PathRelUsr[PATH_MAX + 1];
    unsigned NumID;
 
-   /***** Check if user's code is initialized *****/
+   /***** Trivial check: user's code should be <= 0 *****/
    if (UsrDat->UsrCod > 0)
       Lay_ShowErrorAndExit ("Can not create new user.");
 
diff --git a/swad_agenda.c b/swad_agenda.c
index 979738794..d22c40363 100644
--- a/swad_agenda.c
+++ b/swad_agenda.c
@@ -1178,7 +1178,7 @@ static void Agd_GetListEvents (struct Agd_Agenda *Agenda,
 	      NumEvent++)
 	    /* Get next event code */
 	    if ((Agenda->LstAgdCods[NumEvent] = DB_GetNextCode (mysql_res)) < 0)
-	       Lay_ShowErrorAndExit ("Error: wrong event code.");
+	       Lay_WrongEventExit ();
 	}
 
       /***** Free structure that stores the query result *****/
@@ -1326,8 +1326,8 @@ void Agd_AskRemEvent (void)
    Agd_GetParams (&Agenda,Agd_MY_AGENDA);
 
    /***** Get event code *****/
-   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of event is missing.");
+   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the event from database *****/
    AgdEvent.UsrCod = Gbl.Usrs.Me.UsrDat.UsrCod;
@@ -1362,8 +1362,8 @@ void Agd_RemoveEvent (void)
    Agd_GetParams (&Agenda,Agd_MY_AGENDA);
 
    /***** Get event code *****/
-   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of event is missing.");
+   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the event from database *****/
    AgdEvent.UsrCod = Gbl.Usrs.Me.UsrDat.UsrCod;
@@ -1401,8 +1401,8 @@ void Agd_HideEvent (void)
    Agd_GetParams (&Agenda,Agd_MY_AGENDA);
 
    /***** Get event code *****/
-   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of event is missing.");
+   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the event from database *****/
    AgdEvent.UsrCod = Gbl.Usrs.Me.UsrDat.UsrCod;
@@ -1437,8 +1437,8 @@ void Agd_UnhideEvent (void)
    Agd_GetParams (&Agenda,Agd_MY_AGENDA);
 
    /***** Get event code *****/
-   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of event is missing.");
+   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the event from database *****/
    AgdEvent.UsrCod = Gbl.Usrs.Me.UsrDat.UsrCod;
@@ -1474,8 +1474,8 @@ void Agd_MakeEventPrivate (void)
    Agd_GetParams (&Agenda,Agd_MY_AGENDA);
 
    /***** Get event code *****/
-   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of event is missing.");
+   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the event from database *****/
    AgdEvent.UsrCod = Gbl.Usrs.Me.UsrDat.UsrCod;
@@ -1515,8 +1515,8 @@ void Agd_MakeEventPublic (void)
    Agd_GetParams (&Agenda,Agd_MY_AGENDA);
 
    /***** Get event code *****/
-   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of event is missing.");
+   if ((AgdEvent.AgdCod = Agd_GetParamAgdCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the event from database *****/
    AgdEvent.UsrCod = Gbl.Usrs.Me.UsrDat.UsrCod;
diff --git a/swad_attendance.c b/swad_attendance.c
index 5d13e2d61..07b3d29b1 100644
--- a/swad_attendance.c
+++ b/swad_attendance.c
@@ -720,7 +720,7 @@ static void Att_GetListAttEvents (struct Att_Events *Events,
         {
          /* Get next attendance event code */
          if ((Events->Lst[NumAttEvent].AttCod = DB_GetNextCode (mysql_res)) < 0)
-            Lay_ShowErrorAndExit ("Error: wrong attendance event code.");
+            Lay_WrongEventExit ();
         }
      }
 
@@ -739,10 +739,10 @@ static void Att_GetDataOfAttEventByCodAndCheckCrs (struct Att_Event *Event)
    if (Att_GetDataOfAttEventByCod (Event))
      {
       if (Event->CrsCod != Gbl.Hierarchy.Crs.CrsCod)
-         Lay_ShowErrorAndExit ("Attendance event does not belong to current course.");
+         Lay_WrongEventExit ();
      }
    else	// Attendance event not found
-      Lay_ShowErrorAndExit ("Error when getting attendance event.");
+      Lay_WrongEventExit ();
   }
 
 /*****************************************************************************/
@@ -919,8 +919,8 @@ void Att_AskRemAttEvent (void)
    Events.CurrentPage = Pag_GetParamPagNum (Pag_ATT_EVENTS);
 
    /***** Get attendance event code *****/
-   if ((Event.AttCod = Att_GetParamAttCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of attendance event is missing.");
+   if ((Event.AttCod = Att_GetParamAttCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the attendance event from database *****/
    Att_GetDataOfAttEventByCodAndCheckCrs (&Event);
@@ -954,8 +954,8 @@ void Att_GetAndRemAttEvent (void)
    struct Att_Event Event;
 
    /***** Get attendance event code *****/
-   if ((Event.AttCod = Att_GetParamAttCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of attendance event is missing.");
+   if ((Event.AttCod = Att_GetParamAttCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the attendance event from database *****/
    // Inside this function, the course is checked to be the current one
@@ -997,8 +997,8 @@ void Att_HideAttEvent (void)
    struct Att_Event Event;
 
    /***** Get attendance event code *****/
-   if ((Event.AttCod = Att_GetParamAttCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of attendance event is missing.");
+   if ((Event.AttCod = Att_GetParamAttCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the attendance event from database *****/
    Att_GetDataOfAttEventByCodAndCheckCrs (&Event);
@@ -1025,8 +1025,8 @@ void Att_ShowAttEvent (void)
    struct Att_Event Event;
 
    /***** Get attendance event code *****/
-   if ((Event.AttCod = Att_GetParamAttCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of attendance event is missing.");
+   if ((Event.AttCod = Att_GetParamAttCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Get data of the attendance event from database *****/
    Att_GetDataOfAttEventByCodAndCheckCrs (&Event);
@@ -1861,8 +1861,8 @@ void Att_SeeOneAttEvent (void)
    Att_ResetEvents (&Events);
 
    /***** Get attendance event code *****/
-   if ((Events.AttCod = Att_GetParamAttCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of attendance event is missing.");
+   if ((Events.AttCod = Att_GetParamAttCod ()) < 0)
+      Lay_WrongEventExit ();
 
    /***** Show event *****/
    Att_ShowEvent (&Events);
@@ -2306,8 +2306,8 @@ void Att_RegisterMeAsStdInAttEvent (void)
    Att_ResetEvents (&Events);
 
    /***** Get attendance event code *****/
-   if ((Event.AttCod = Att_GetParamAttCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of attendance event is missing.");
+   if ((Event.AttCod = Att_GetParamAttCod ()) < 0)
+      Lay_WrongEventExit ();
    Att_GetDataOfAttEventByCodAndCheckCrs (&Event);	// This checks that event belong to current course
 
    if (Event.Open)
@@ -2371,8 +2371,8 @@ void Att_RegisterStudentsInAttEvent (void)
    Att_ResetEvents (&Events);
 
    /***** Get attendance event code *****/
-   if ((Event.AttCod = Att_GetParamAttCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of attendance event is missing.");
+   if ((Event.AttCod = Att_GetParamAttCod ()) < 0)
+      Lay_WrongEventExit ();
    Att_GetDataOfAttEventByCodAndCheckCrs (&Event);	// This checks that event belong to current course
 
    /***** Get groups selected *****/
diff --git a/swad_center.c b/swad_center.c
index e5d27a459..6d860634e 100644
--- a/swad_center.c
+++ b/swad_center.c
@@ -750,7 +750,7 @@ static void Ctr_GetDataOfCenterFromRow (struct Ctr_Center *Ctr,MYSQL_ROW row)
   {
    /***** Get center code (row[0]) *****/
    if ((Ctr->CtrCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of center.");
+      Lay_WrongCenterExit ();
 
    /***** Get institution code (row[1]) *****/
    Ctr->InsCod = Str_ConvertStrCodToLongCod (row[1]);
@@ -881,7 +881,7 @@ void Ctr_WriteSelectorOfCenter (void)
 
          /* Get center code (row[0]) */
          if ((CtrCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of center.");
+            Lay_WrongCenterExit ();
 
          /* Write option */
 	 HTM_OPTION (HTM_Type_LONG,&CtrCod,
@@ -1185,7 +1185,7 @@ long Ctr_GetAndCheckParamOtherCtrCod (long MinCodAllowed)
 
    /***** Get and check parameter with code of center *****/
    if ((CtrCod = Par_GetParToLong ("OthCtrCod")) < MinCodAllowed)
-      Lay_ShowErrorAndExit ("Code of center is missing or invalid.");
+      Lay_WrongCenterExit ();
 
    return CtrCod;
   }
@@ -2283,7 +2283,7 @@ static void Ctr_EditingCenterConstructor (void)
   {
    /***** Pointer must be NULL *****/
    if (Ctr_EditingCtr != NULL)
-      Lay_ShowErrorAndExit ("Error initializing center.");
+      Lay_WrongCenterExit ();
 
    /***** Allocate memory for center *****/
    if ((Ctr_EditingCtr = malloc (sizeof (*Ctr_EditingCtr))) == NULL)
diff --git a/swad_changelog.h b/swad_changelog.h
index b22ea026c..063ba38b6 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -600,13 +600,14 @@ TODO: Salvador Romero Cort
 
 TODO: FIX BUG, URGENT! En las fechas como parámetro Dat_WriteParamsIniEndDates(), por ejemplo al cambiar el color de la gráfica de accesos por día y hora, no se respeta la zona horaria.
 */
-#define Log_PLATFORM_VERSION	"SWAD 20.67 (2021-04-24)"
+#define Log_PLATFORM_VERSION	"SWAD 20.67.1 (2021-04-24)"
 #define CSS_FILE		"swad20.45.css"
 #define JS_FILE			"swad20.6.2.js"
 /*
 TODO: Rename CENTRE to CENTER in help wiki.
 TODO: Rename ASSESSMENT.Announcements to ASSESSMENT.Calls_for_exams
 
+	Version 20.67.1:  Apr 24, 2021  Code refactoring in error messages. (309415 lines)
 	Version 20.67:    Apr 24, 2021  Bug fixing and code optimizations related to user's roles. (309356 lines)
 	Version 20.66.5:  Apr 23, 2021  Including missing head files.
 					Fixed bug getting my courses. (309123 lines)
diff --git a/swad_chat.c b/swad_chat.c
index 8f211687e..1991a279d 100644
--- a/swad_chat.c
+++ b/swad_chat.c
@@ -176,7 +176,7 @@ void Cht_ShowListOfAvailableChatRooms (void)
       /* Get data of this degree */
       Deg.DegCod = Gbl.Usrs.Me.MyDegs.Degs[NumMyDeg].DegCod;
       if (!Deg_GetDataOfDegreeByCod (&Deg))
-         Lay_ShowErrorAndExit ("Degree not found.");
+         Lay_WrongDegreeExit ();
 
       /* Link to the room of this degree */
       IsLastItemInLevel[1] = (NumMyDeg == Gbl.Usrs.Me.MyDegs.Num - 1);
diff --git a/swad_country.c b/swad_country.c
index c86e4db72..a58028751 100644
--- a/swad_country.c
+++ b/swad_country.c
@@ -786,7 +786,7 @@ void Cty_GetBasicListOfCountries (void)
 
          /* Get numerical country code (row[0]) */
          if ((Cty->CtyCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of country.");
+            Lay_WrongCountrExit ();
 
          /* Get Alpha-2 country code (row[1]) */
          Str_Copy (Cty->Alpha2,row[1],sizeof (Cty->Alpha2) - 1);
@@ -912,7 +912,7 @@ void Cty_GetFullListOfCountries (void)
 
          /* Get numerical country code (row[0]) */
          if ((Cty->CtyCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of country.");
+            Lay_WrongCountrExit ();
 
          /* Get Alpha-2 country code (row[1]) */
          Str_Copy (Cty->Alpha2,row[1],sizeof (Cty->Alpha2) - 1);
@@ -981,7 +981,7 @@ void Cty_WriteSelectorOfCountry (void)
 
       /* Get country code (row[0]) */
       if ((CtyCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of country.");
+         Lay_WrongCountrExit ();
 
       /* Write option */
       HTM_OPTION (HTM_Type_LONG,&CtyCod,
@@ -1302,7 +1302,7 @@ long Cty_GetAndCheckParamOtherCtyCod (long MinCodAllowed)
 
    /***** Get and check parameter with code of country *****/
    if ((CtyCod = Cty_GetParamOtherCtyCod ()) < MinCodAllowed)
-      Lay_ShowErrorAndExit ("Code of country is missing or invalid.");
+      Lay_WrongCountrExit ();
 
    return CtyCod;
   }
@@ -2119,7 +2119,7 @@ static void Cty_EditingCountryConstructor (void)
 
    /***** Pointer must be NULL *****/
    if (Cty_EditingCty != NULL)
-      Lay_ShowErrorAndExit ("Error initializing country.");
+      Lay_WrongCountrExit ();
 
    /***** Allocate memory for country *****/
    if ((Cty_EditingCty = malloc (sizeof (*Cty_EditingCty))) == NULL)
diff --git a/swad_course.c b/swad_course.c
index c0b49cd38..e52547363 100644
--- a/swad_course.c
+++ b/swad_course.c
@@ -215,7 +215,7 @@ static void Crs_WriteListMyCoursesToSelectOne (void)
       /***** Get data of this institution *****/
       Hie.Cty.CtyCod = Str_ConvertStrCodToLongCod (row[0]);
       if (!Cty_GetDataOfCountryByCod (&Hie.Cty))
-	 Lay_ShowErrorAndExit ("Country not found.");
+	 Lay_WrongCountrExit ();
 
       /***** Write link to country *****/
       Highlight = (Gbl.Hierarchy.Ins.InsCod <= 0 &&
@@ -249,7 +249,7 @@ static void Crs_WriteListMyCoursesToSelectOne (void)
 	 /***** Get data of this institution *****/
 	 Hie.Ins.InsCod = Str_ConvertStrCodToLongCod (row[0]);
 	 if (!Ins_GetDataOfInstitutionByCod (&Hie.Ins))
-	    Lay_ShowErrorAndExit ("Institution not found.");
+	    Lay_WrongInstitExit ();
 
 	 /***** Write link to institution *****/
 	 Highlight = (Gbl.Hierarchy.Ctr.CtrCod <= 0 &&
@@ -283,7 +283,7 @@ static void Crs_WriteListMyCoursesToSelectOne (void)
 	    /***** Get data of this center *****/
 	    Hie.Ctr.CtrCod = Str_ConvertStrCodToLongCod (row[0]);
 	    if (!Ctr_GetDataOfCenterByCod (&Hie.Ctr))
-	       Lay_ShowErrorAndExit ("Center not found.");
+	       Lay_WrongCenterExit ();
 
 	    /***** Write link to center *****/
 	    Highlight = (Gbl.Hierarchy.Level == Hie_Lvl_CTR &&
@@ -317,7 +317,7 @@ static void Crs_WriteListMyCoursesToSelectOne (void)
 	       /***** Get data of this degree *****/
 	       Hie.Deg.DegCod = Str_ConvertStrCodToLongCod (row[0]);
 	       if (!Deg_GetDataOfDegreeByCod (&Hie.Deg))
-		  Lay_ShowErrorAndExit ("Degree not found.");
+		  Lay_WrongDegreeExit ();
 
 	       /***** Write link to degree *****/
 	       Highlight = (Gbl.Hierarchy.Level == Hie_Lvl_DEG &&
@@ -351,7 +351,7 @@ static void Crs_WriteListMyCoursesToSelectOne (void)
 		  /***** Get data of this course *****/
 		  Hie.Crs.CrsCod = Str_ConvertStrCodToLongCod (row[0]);
 		  if (!Crs_GetDataOfCourseByCod (&Hie.Crs))
-		     Lay_ShowErrorAndExit ("Course not found.");
+		     Lay_WrongCourseExit ();
 
 		  /***** Write link to course *****/
 		  Highlight = (Gbl.Hierarchy.Level == Hie_Lvl_CRS &&
@@ -711,7 +711,7 @@ void Crs_WriteSelectorOfCourse (void)
 
          /* Get course code (row[0]) */
          if ((CrsCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong course.");
+            Lay_WrongCourseExit ();
 
          /* Write option */
 	 HTM_OPTION (HTM_Type_LONG,&CrsCod,
@@ -1833,7 +1833,7 @@ static void Crs_GetDataOfCourseFromRow (struct Crs_Course *Crs,MYSQL_ROW row)
   {
    /***** Get course code (row[0]) *****/
    if ((Crs->CrsCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-      Lay_ShowErrorAndExit ("Wrong code of course.");
+      Lay_WrongCourseExit ();
 
    /***** Get code of degree (row[1]) *****/
    Crs->DegCod = Str_ConvertStrCodToLongCod (row[1]);
@@ -2619,7 +2619,7 @@ static long Crs_GetAndCheckParamOtherCrsCod (long MinCodAllowed)
 
    /***** Get and check parameter with code of course *****/
    if ((CrsCod = Par_GetParToLong ("OthCrsCod")) < MinCodAllowed)
-      Lay_ShowErrorAndExit ("Code of course is missing or invalid.");
+      Lay_WrongCourseExit ();
 
    return CrsCod;
   }
@@ -2826,13 +2826,13 @@ static void Crs_WriteRowCrsData (unsigned NumCrs,MYSQL_ROW row,bool WriteColumnA
 
    /***** Get degree code (row[0]) *****/
    if ((Deg.DegCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-      Lay_ShowErrorAndExit ("Wrong code of degree.");
+      Lay_WrongDegreeExit ();
    if (!Deg_GetDataOfDegreeByCod (&Deg))
-      Lay_ShowErrorAndExit ("Degree not found.");
+      Lay_WrongDegreeExit ();
 
    /***** Get course code (row[1]) *****/
    if ((CrsCod = Str_ConvertStrCodToLongCod (row[1])) < 0)
-      Lay_ShowErrorAndExit ("Wrong code of course.");
+      Lay_WrongCourseExit ();
 
    /***** Get number of teachers and students in this course *****/
    NumStds = Usr_GetNumUsrsInCrss (Hie_Lvl_CRS,CrsCod,1 << Rol_STD);
@@ -3071,7 +3071,7 @@ static void Crs_EditingCourseConstructor (void)
   {
    /***** Pointer must be NULL *****/
    if (Crs_EditingCrs != NULL)
-      Lay_ShowErrorAndExit ("Error initializing course.");
+      Lay_WrongCourseExit ();
 
    /***** Allocate memory for course *****/
    if ((Crs_EditingCrs = malloc (sizeof (*Crs_EditingCrs))) == NULL)
diff --git a/swad_degree.c b/swad_degree.c
index 2c8163000..1b5bd7b4d 100644
--- a/swad_degree.c
+++ b/swad_degree.c
@@ -296,7 +296,7 @@ void Deg_WriteSelectorOfDegree (void)
 
          /* Get degree code (row[0]) */
          if ((DegCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong degree.");
+            Lay_WrongDegreeExit ();
 
          /* Write option */
 	 HTM_OPTION (HTM_Type_LONG,&DegCod,
@@ -1339,7 +1339,7 @@ long Deg_GetAndCheckParamOtherDegCod (long MinCodAllowed)
 
    /***** Get and check parameter with code of degree *****/
    if ((DegCod = Par_GetParToLong ("OthDegCod")) < MinCodAllowed)
-      Lay_ShowErrorAndExit ("Code of degree is missing or invalid.");
+      Lay_WrongDegreeExit ();
 
    return DegCod;
   }
@@ -1404,7 +1404,7 @@ static void Deg_GetDataOfDegreeFromRow (struct Deg_Degree *Deg,MYSQL_ROW row)
   {
    /***** Get degree code (row[0]) *****/
    if ((Deg->DegCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-      Lay_ShowErrorAndExit ("Wrong code of degree.");
+      Lay_WrongDegreeExit ();
 
    /***** Get center code (row[1]) *****/
    Deg->CtrCod = Str_ConvertStrCodToLongCod (row[1]);
@@ -1512,7 +1512,7 @@ void Deg_RemoveDegreeCompletely (long DegCod)
      {
       /* Get next course */
       if ((CrsCod = DB_GetNextCode (mysql_res)) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of course.");
+         Lay_WrongCourseExit ();
 
       /* Remove course */
       Crs_RemoveCourseCompletely (CrsCod);
@@ -2197,7 +2197,7 @@ static void Deg_EditingDegreeConstructor (void)
   {
    /***** Pointer must be NULL *****/
    if (Deg_EditingDeg != NULL)
-      Lay_ShowErrorAndExit ("Error initializing degree.");
+      Lay_WrongDegreeExit ();
 
    /***** Allocate memory for degree *****/
    if ((Deg_EditingDeg = malloc (sizeof (*Deg_EditingDeg))) == NULL)
diff --git a/swad_degree_type.c b/swad_degree_type.c
index 5e390b3ed..0bffb4da5 100644
--- a/swad_degree_type.c
+++ b/swad_degree_type.c
@@ -921,7 +921,7 @@ static void DT_RemoveDegreeTypeCompletely (long DegTypCod)
      {
       /* Get next degree */
       if ((DegCod = DB_GetNextCode (mysql_res)) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of degree.");
+         Lay_WrongDegreeExit ();
 
       /* Remove degree */
       Deg_RemoveDegreeCompletely (DegCod);
diff --git a/swad_department.c b/swad_department.c
index 26a090975..d4419c449 100644
--- a/swad_department.c
+++ b/swad_department.c
@@ -395,7 +395,7 @@ static void Dpt_GetListDepartments (struct Dpt_Departments *Departments,long Ins
 
 	    /* Get institution code (row[1]) */
 	    if ((Dpt->InsCod = Str_ConvertStrCodToLongCod (row[1])) < 0)
-	       Lay_ShowErrorAndExit ("Wrong code of institution.");
+	       Lay_WrongInstitExit ();
 
 	    /* Get short name (row[2]), full name (row[3])
 	       and URL (row[4]) of the department  */
diff --git a/swad_enrolment.c b/swad_enrolment.c
index 9a077310a..9df1192bd 100644
--- a/swad_enrolment.c
+++ b/swad_enrolment.c
@@ -4348,7 +4348,7 @@ static void Enr_AskIfRemAdm (bool ItsMe,Hie_Lvl_Level_t Scope,
                                        Txt_Remove_USER_as_an_administrator);
      }
    else
-      Lay_ShowErrorAndExit ("User doesn't exist.");
+      Ale_ShowAlertUserNotFoundOrYouDoNotHavePermission ();
   }
 
 /*****************************************************************************/
diff --git a/swad_exam.c b/swad_exam.c
index 0017d7f97..871c9ae15 100644
--- a/swad_exam.c
+++ b/swad_exam.c
@@ -863,7 +863,7 @@ void Exa_GetListExams (struct Exa_Exams *Exams,Exa_Order_t SelectedOrder)
          /* Get next exam code (row[0]) */
          row = mysql_fetch_row (mysql_res);
          if ((Exams->Lst[NumExam].ExaCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
-            Lay_ShowErrorAndExit ("Error: wrong exam code.");
+            Lay_WrongExamExit ();
         }
      }
 
@@ -1130,8 +1130,8 @@ void Exa_RemoveExam (void)
    Exa_ResetExam (&Exam);
 
    /***** Get exam code *****/
-   if ((Exam.ExaCod = Exa_GetParamExamCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of exam is missing.");
+   if ((Exam.ExaCod = Exa_GetParamExamCod ()) <= 0)
+      Lay_WrongExamExit ();
 
    /***** Get data of the exam from database *****/
    Exa_GetDataOfExamByCod (&Exam);
diff --git a/swad_exam_print.c b/swad_exam_print.c
index bbbccb63b..335e4bdb3 100644
--- a/swad_exam_print.c
+++ b/swad_exam_print.c
@@ -635,11 +635,11 @@ void ExaPrn_GetPrintQuestionsFromDB (struct ExaPrn_Print *Print)
 
 	 /* Get question code (row[0]) */
 	 if ((Print->PrintedQuestions[NumQst].QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of question.");
+	    Lay_WrongQuestionExit ();
 
 	 /* Get set code (row[1]) */
 	 if ((Print->PrintedQuestions[NumQst].SetCod = Str_ConvertStrCodToLongCod (row[1])) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of set.");
+	    Lay_WrongSetExit ();
 
          /* Get score (row[2]) */
 	 Str_SetDecimalPointToUS ();	// To get the decimal point as a dot
diff --git a/swad_exam_session.c b/swad_exam_session.c
index 5a3f6ab8c..c16bee1ec 100644
--- a/swad_exam_session.c
+++ b/swad_exam_session.c
@@ -870,11 +870,11 @@ static void ExaSes_GetSessionDataFromRow (MYSQL_RES *mysql_res,
    /***** Get session data *****/
    /* Code of the session (row[0]) */
    if ((Session->SesCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of exam session.");
+      Lay_WrongExamSessionExit ();
 
    /* Code of the exam (row[1]) */
    if ((Session->ExaCod = Str_ConvertStrCodToLongCod (row[1])) <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of exam.");
+      Lay_WrongExamExit ();
 
    /* Get whether the session is hidden (row[2]) */
    Session->Hidden = (row[2][0] == 'Y');
diff --git a/swad_exam_set.c b/swad_exam_set.c
index cbc5f6bee..4829b0c2a 100644
--- a/swad_exam_set.c
+++ b/swad_exam_set.c
@@ -785,7 +785,7 @@ static unsigned ExaSet_GetSetIndFromSetCod (long ExaCod,long SetCod)
 			" WHERE SetCod=%u"
 			  " AND ExaCod=%ld",	// Extra check
 			SetCod,ExaCod))
-      Lay_ShowErrorAndExit ("Error: wrong set code.");
+      Lay_WrongSetExit ();
 
    /***** Get set code (row[0]) *****/
    row = mysql_fetch_row (mysql_res);
@@ -814,7 +814,7 @@ static long ExaSet_GetSetCodFromSetInd (long ExaCod,unsigned SetInd)
 				ExaCod,
 				SetInd);
    if (SetCod <= 0)
-      Lay_ShowErrorAndExit ("Error: wrong set index.");
+      Lay_WrongSetExit ();
 
    return SetCod;
   }
@@ -1323,7 +1323,7 @@ Tst_AnswerType_t ExaSet_GetQstAnswerTypeFromDB (long QstCod)
 		        " FROM exa_set_questions"
 		       " WHERE QstCod=%ld",
 		       QstCod))
-      Lay_ShowErrorAndExit ("Question does not exist.");
+      Lay_WrongQuestionExit ();
 
    /* Get type of answer */
    row = mysql_fetch_row (mysql_res);
@@ -1464,7 +1464,7 @@ void ExaSet_GetQstDataFromDB (struct Tst_Question *Question)
    DB_FreeMySQLResult (&mysql_res);
 
    if (!QuestionExists)
-      Lay_ShowErrorAndExit ("Wrong question.");
+      Lay_WrongQuestionExit ();
   }
 
 /*****************************************************************************/
@@ -1596,7 +1596,7 @@ void ExaSet_AddQstsToSet (void)
 	 /* Get next code */
 	 Par_GetNextStrUntilSeparParamMult (&Ptr,LongStr,Cns_MAX_DECIMAL_DIGITS_LONG);
 	 if (sscanf (LongStr,"%ld",&QstCod) != 1)
-	    Lay_ShowErrorAndExit ("Wrong question code.");
+	    Lay_WrongQuestionExit ();
 
 	 ExaSet_CopyQstFromBankToExamSet (&Set,QstCod);
 	}
@@ -2008,7 +2008,7 @@ void ExaSet_RemoveQstFromSet (void)
 		   QstCod,
 		   Set.SetCod);
    if (!mysql_affected_rows (&Gbl.mysql))
-      Lay_ShowErrorAndExit ("The question to be removed does not exist.");
+      Lay_WrongQuestionExit ();
 
    /***** Write message *****/
    Ale_ShowAlert (Ale_SUCCESS,Txt_Question_removed);
diff --git a/swad_figure.c b/swad_figure.c
index 2030b8528..69a4a8208 100644
--- a/swad_figure.c
+++ b/swad_figure.c
@@ -1577,7 +1577,7 @@ static unsigned Fig_GetInsAndStat (struct Ins_Instit *Ins,MYSQL_RES *mysql_res)
    /***** Get data of this institution (row[0]) *****/
    Ins->InsCod = Str_ConvertStrCodToLongCod (row[0]);
    if (!Ins_GetDataOfInstitutionByCod (Ins))
-      Lay_ShowErrorAndExit ("Institution not found.");
+      Lay_WrongInstitExit ();
 
    /***** Get statistic (row[1]) *****/
    if (sscanf (row[1],"%u",&NumberThisRow) != 1)
diff --git a/swad_forum.c b/swad_forum.c
index 7736dace9..5a3aba9ed 100644
--- a/swad_forum.c
+++ b/swad_forum.c
@@ -2215,13 +2215,13 @@ void For_SetForumName (const struct For_Forum *Forum,
       case For_FORUM_INSTIT_USRS:
 	 Hie.Ins.InsCod = Forum->Location;
 	 if (!Ins_GetDataOfInstitutionByCod (&Hie.Ins))
-	    Lay_ShowErrorAndExit ("Institution not found.");
+	    Lay_WrongInstitExit ();
          Str_Copy (ForumName,Hie.Ins.ShrtName,For_MAX_BYTES_FORUM_NAME);
          break;
       case For_FORUM_INSTIT_TCHS:
 	 Hie.Ins.InsCod = Forum->Location;
 	 if (!Ins_GetDataOfInstitutionByCod (&Hie.Ins))
-	    Lay_ShowErrorAndExit ("Institution not found.");
+	    Lay_WrongInstitExit ();
          snprintf (ForumName,For_MAX_BYTES_FORUM_NAME + 1,"%s%s",
                    Hie.Ins.ShrtName,
                    UseHTMLEntities ? Txt_only_teachers :
@@ -2230,13 +2230,13 @@ void For_SetForumName (const struct For_Forum *Forum,
       case For_FORUM_CENTER_USRS:
 	 Hie.Ctr.CtrCod = Forum->Location;
 	 if (!Ctr_GetDataOfCenterByCod (&Hie.Ctr))
-	    Lay_ShowErrorAndExit ("Center not found.");
+	    Lay_WrongCenterExit ();
          Str_Copy (ForumName,Hie.Ctr.ShrtName,For_MAX_BYTES_FORUM_NAME);
          break;
       case For_FORUM_CENTER_TCHS:
 	 Hie.Ctr.CtrCod = Forum->Location;
 	 if (!Ctr_GetDataOfCenterByCod (&Hie.Ctr))
-	    Lay_ShowErrorAndExit ("Center not found.");
+	    Lay_WrongCenterExit ();
          snprintf (ForumName,For_MAX_BYTES_FORUM_NAME + 1,"%s%s",
                    Hie.Ctr.ShrtName,
                    UseHTMLEntities ? Txt_only_teachers :
@@ -2245,13 +2245,13 @@ void For_SetForumName (const struct For_Forum *Forum,
       case For_FORUM_DEGREE_USRS:
 	 Hie.Deg.DegCod = Forum->Location;
 	 if (!Deg_GetDataOfDegreeByCod (&Hie.Deg))
-	    Lay_ShowErrorAndExit ("Degree not found.");
+	    Lay_WrongDegreeExit ();
          Str_Copy (ForumName,Hie.Deg.ShrtName,For_MAX_BYTES_FORUM_NAME);
          break;
       case For_FORUM_DEGREE_TCHS:
 	 Hie.Deg.DegCod = Forum->Location;
 	 if (!Deg_GetDataOfDegreeByCod (&Hie.Deg))
-	    Lay_ShowErrorAndExit ("Degree not found.");
+	    Lay_WrongDegreeExit ();
          snprintf (ForumName,For_MAX_BYTES_FORUM_NAME + 1,"%s%s",
                    Hie.Deg.ShrtName,
                    UseHTMLEntities ? Txt_only_teachers :
@@ -2260,13 +2260,13 @@ void For_SetForumName (const struct For_Forum *Forum,
       case For_FORUM_COURSE_USRS:
 	 Hie.Crs.CrsCod = Forum->Location;
 	 if (!Crs_GetDataOfCourseByCod (&Hie.Crs))
-	    Lay_ShowErrorAndExit ("Course not found.");
+	    Lay_WrongCourseExit ();
          Str_Copy (ForumName,Hie.Crs.ShrtName,For_MAX_BYTES_FORUM_NAME);
          break;
       case For_FORUM_COURSE_TCHS:
 	 Hie.Crs.CrsCod = Forum->Location;
 	 if (!Crs_GetDataOfCourseByCod (&Hie.Crs))
-	    Lay_ShowErrorAndExit ("Course not found.");
+	    Lay_WrongCourseExit ();
          snprintf (ForumName,For_MAX_BYTES_FORUM_NAME + 1,"%s%s",
                    Hie.Crs.ShrtName,
                    UseHTMLEntities ? Txt_only_teachers :
diff --git a/swad_game.c b/swad_game.c
index 5511c7974..7fe671dc1 100644
--- a/swad_game.c
+++ b/swad_game.c
@@ -469,7 +469,7 @@ void Gam_SeeOneGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Show game *****/
@@ -929,7 +929,7 @@ void Gam_GetListGames (struct Gam_Games *Games,Gam_Order_t SelectedOrder)
          /* Get next game code (row[0]) */
          row = mysql_fetch_row (mysql_res);
          if ((Games->Lst[NumGame].GamCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
-            Lay_ShowErrorAndExit ("Error: wrong game code.");
+            Lay_WrongGameExit ();
         }
      }
 
@@ -1154,7 +1154,7 @@ void Gam_AskRemGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
 
    /***** Get data of the game from database *****/
    Gam_GetDataOfGameByCod (&Game);
@@ -1190,8 +1190,8 @@ void Gam_RemoveGame (void)
    Gam_ResetGame (&Game);
 
    /***** Get game code *****/
-   if ((Game.GamCod = Gam_GetParamGameCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+   if ((Game.GamCod = Gam_GetParamGameCod ()) <= 0)
+      Lay_WrongGameExit ();
 
    /***** Get data of the game from database *****/
    Gam_GetDataOfGameByCod (&Game);
@@ -1273,7 +1273,7 @@ void Gam_HideGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
 
    /***** Get data of the game from database *****/
    Gam_GetDataOfGameByCod (&Game);
@@ -1308,7 +1308,7 @@ void Gam_UnhideGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
 
    /***** Get data of the game from database *****/
    Gam_GetDataOfGameByCod (&Game);
@@ -1366,7 +1366,7 @@ void Gam_ListGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
 
    /***** Get game data *****/
    Gam_GetDataOfGameByCod (&Game);
@@ -1738,7 +1738,7 @@ void Gam_ReqSelectQstsToAddToGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Check if game has matches *****/
@@ -1772,7 +1772,7 @@ void Gam_ListQstsToAddToGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Check if game has matches *****/
@@ -2170,7 +2170,7 @@ void Gam_AddQstsToGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Check if game has matches *****/
@@ -2196,7 +2196,7 @@ void Gam_AddQstsToGame (void)
 	 /* Get next code */
 	 Par_GetNextStrUntilSeparParamMult (&Ptr,LongStr,Cns_MAX_DECIMAL_DIGITS_LONG);
 	 if (sscanf (LongStr,"%ld",&QstCod) != 1)
-	    Lay_ShowErrorAndExit ("Wrong question code.");
+	    Lay_WrongQuestionExit ();
 
 	 /* Check if question is already present in game */
 	 if (Gam_GetQstIndFromQstCod (Game.GamCod,QstCod) == 0)	// This question is not yet in this game
@@ -2283,7 +2283,7 @@ void Gam_RequestRemoveQstFromGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Check if game has matches *****/
@@ -2327,7 +2327,7 @@ void Gam_RemoveQstFromGame (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Check if game has matches *****/
@@ -2349,7 +2349,7 @@ void Gam_RemoveQstFromGame (void)
 		   Game.GamCod,
 		   QstInd);
    if (!mysql_affected_rows (&Gbl.mysql))
-      Lay_ShowErrorAndExit ("The question to be removed does not exist.");
+      Lay_WrongQuestionExit ();
 
    /* Change index of questions greater than this */
    DB_QueryUPDATE ("can not update indexes of questions in table of answers",
@@ -2398,7 +2398,7 @@ void Gam_MoveUpQst (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Check if game has matches *****/
@@ -2449,7 +2449,7 @@ void Gam_MoveDownQst (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Check if game has matches *****/
@@ -2599,7 +2599,7 @@ void Gam_RequestNewMatch (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Show game *****/
diff --git a/swad_group.c b/swad_group.c
index f54ffe195..7f312dfe1 100644
--- a/swad_group.c
+++ b/swad_group.c
@@ -3219,7 +3219,7 @@ void Grp_GetDataOfGroupByCod (struct GroupData *GrpDat)
 
 	 /* Get the code of the course (row[1]) */
 	 if ((GrpDat->CrsCod = Str_ConvertStrCodToLongCod (row[1])) <= 0)
-	    Lay_ShowErrorAndExit ("Wrong code of course.");
+	    Lay_WrongCourseExit ();
 
 	 /* Get the name of the group type (row[2]) */
 	 Str_Copy (GrpDat->GrpTypName,row[2],sizeof (GrpDat->GrpTypName) - 1);
diff --git a/swad_indicator.c b/swad_indicator.c
index 7baff7299..a2d3c2e15 100644
--- a/swad_indicator.c
+++ b/swad_indicator.c
@@ -723,7 +723,7 @@ static void Ind_GetNumCoursesWithIndicators (unsigned NumCrssWithIndicatorYes[1
 
       /* Get course code (row[2]) */
       if ((CrsCod = Str_ConvertStrCodToLongCod (row[2])) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of course.");
+         Lay_WrongCourseExit ();
 
       /* Get stored number of indicators of this course */
       NumIndicators = Ind_GetAndUpdateNumIndicatorsCrs (CrsCod);
@@ -991,7 +991,7 @@ static void Ind_ShowTableOfCoursesWithIndicators (const struct Ind_Indicators *I
 
       /* Get course code (row[2]) */
       if ((CrsCod = Str_ConvertStrCodToLongCod (row[2])) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of course.");
+         Lay_WrongCourseExit ();
 
       /* Get stored number of indicators of this course */
       NumIndicators = Ind_GetAndUpdateNumIndicatorsCrs (CrsCod);
diff --git a/swad_institution.c b/swad_institution.c
index e127a0b91..7c8e9760f 100644
--- a/swad_institution.c
+++ b/swad_institution.c
@@ -835,7 +835,7 @@ static void Ins_GetDataOfInstitFromRow (struct Ins_Instit *Ins,MYSQL_ROW row)
   {
    /***** Get institution code (row[0]) *****/
    if ((Ins->InsCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-      Lay_ShowErrorAndExit ("Wrong code of institution.");
+      Lay_WrongInstitExit ();
 
    /***** Get country code (row[1]) *****/
    Ins->CtyCod = Str_ConvertStrCodToLongCod (row[1]);
@@ -1030,7 +1030,7 @@ void Ins_WriteSelectorOfInstitution (void)
 
          /* Get institution code (row[0]) */
          if ((InsCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of institution.");
+            Lay_WrongInstitExit ();
 
          /* Write option */
 	 HTM_OPTION (HTM_Type_LONG,&InsCod,
@@ -1314,7 +1314,7 @@ long Ins_GetAndCheckParamOtherInsCod (long MinCodAllowed)
 
    /***** Get and check parameter with code of institution *****/
    if ((InsCod = Ins_GetParamOtherInsCod ()) < MinCodAllowed)
-      Lay_ShowErrorAndExit ("Code of institution is missing or invalid.");
+      Lay_WrongInstitExit ();
 
    return InsCod;
   }
@@ -2174,7 +2174,7 @@ static void Ins_EditingInstitutionConstructor (void)
   {
    /***** Pointer must be NULL *****/
    if (Ins_EditingIns != NULL)
-      Lay_ShowErrorAndExit ("Error initializing institution.");
+      Lay_WrongInstitExit ();
 
    /***** Allocate memory for institution *****/
    if ((Ins_EditingIns = malloc (sizeof (*Ins_EditingIns))) == NULL)
diff --git a/swad_layout.c b/swad_layout.c
index 1bfbc88fe..d2e06eb54 100644
--- a/swad_layout.c
+++ b/swad_layout.c
@@ -1387,6 +1387,36 @@ void Lay_WrongScopeExit (void)
    Lay_ShowErrorAndExit ("Wrong scope.");
   }
 
+/*****************************************************************************/
+/********* Write error message and exit                              *********/
+/********* when wrong country, institution, center, degree or course *********/
+/*****************************************************************************/
+
+void Lay_WrongCountrExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong country.");
+  }
+
+void Lay_WrongInstitExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong institution.");
+  }
+
+void Lay_WrongCenterExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong center.");
+  }
+
+void Lay_WrongDegreeExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong degree.");
+  }
+
+void Lay_WrongCourseExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong course.");
+  }
+
 /*****************************************************************************/
 /************* Write error message and exit when wrong order *****************/
 /*****************************************************************************/
@@ -1441,6 +1471,15 @@ void Lay_WrongSetExit (void)
    Lay_ShowErrorAndExit ("Wrong set of questions.");
   }
 
+/*****************************************************************************/
+/************* Write error message and exit when wrong question **************/
+/*****************************************************************************/
+
+void Lay_WrongQuestionExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong question.");
+  }
+
 /*****************************************************************************/
 /*********** Write error message and exit when wrong exam session ************/
 /*****************************************************************************/
@@ -1450,6 +1489,20 @@ void Lay_WrongExamSessionExit (void)
    Lay_ShowErrorAndExit ("Wrong exam session.");
   }
 
+/*****************************************************************************/
+/************ Write error message and exit when wrong game/match *************/
+/*****************************************************************************/
+
+void Lay_WrongGameExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong game.");
+  }
+
+void Lay_WrongMatchExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong match.");
+  }
+
 /*****************************************************************************/
 /*** Write error message and exit when wrong parameter "who" (which users) ***/
 /*****************************************************************************/
@@ -1459,6 +1512,15 @@ void Lay_WrongWhoExit (void)
    Lay_ShowErrorAndExit ("Wrong parameter who.");
   }
 
+/*****************************************************************************/
+/**************** Write error message and exit when wrong event **************/
+/*****************************************************************************/
+
+void Lay_WrongEventExit (void)
+  {
+   Lay_ShowErrorAndExit ("Wrong event.");
+  }
+
 /*****************************************************************************/
 /************ Write error message and exit when user does not exists *********/
 /*****************************************************************************/
diff --git a/swad_layout.h b/swad_layout.h
index d964affaf..4ef32ef75 100644
--- a/swad_layout.h
+++ b/swad_layout.h
@@ -71,14 +71,23 @@ void Lay_PutContextualCheckbox (Act_Action_t NextAction,
 
 void Lay_NotEnoughMemoryExit (void);
 void Lay_WrongScopeExit (void);
+void Lay_WrongCountrExit (void);
+void Lay_WrongInstitExit (void);
+void Lay_WrongCenterExit (void);
+void Lay_WrongDegreeExit (void);
+void Lay_WrongCourseExit (void);
 void Lay_WrongOrderExit (void);
 void Lay_WrongTypeOfViewExit (void);
 void Lay_WrongProjectExit (void);
 void Lay_WrongCallForExamExit (void);
 void Lay_WrongExamExit (void);
 void Lay_WrongSetExit (void);
+void Lay_WrongQuestionExit (void);
 void Lay_WrongExamSessionExit (void);
+void Lay_WrongGameExit (void);
+void Lay_WrongMatchExit (void);
 void Lay_WrongWhoExit (void);
+void Lay_WrongEventExit (void);
 void Lay_WrongUserExit (void);
 void Lay_NoPermissionExit (void);
 void Lay_ShowErrorAndExit (const char *Txt);
diff --git a/swad_match.c b/swad_match.c
index 91bcaa6e2..49d68ee7e 100644
--- a/swad_match.c
+++ b/swad_match.c
@@ -1014,11 +1014,11 @@ static void Mch_GetMatchDataFromRow (MYSQL_RES *mysql_res,
    /***** Get match data *****/
    /* Code of the match (row[0]) */
    if ((Match->MchCod = Str_ConvertStrCodToLongCod (row[0])) <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of match.");
+      Lay_WrongMatchExit ();
 
    /* Code of the game (row[1]) */
    if ((Match->GamCod = Str_ConvertStrCodToLongCod (row[1])) <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of game.");
+      Lay_WrongGameExit ();
 
    /* Get match teacher (row[2]) */
    Match->UsrCod = Str_ConvertStrCodToLongCod (row[2]);
@@ -1409,20 +1409,20 @@ void Mch_GetAndCheckParameters (struct Gam_Games *Games,
    /***** Get parameters *****/
    /* Get parameters of game */
    if ((Game->GamCod = Gam_GetParams (Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Grp_GetParamWhichGroups ();
    Gam_GetDataOfGameByCod (Game);
 
    /* Get match code */
    if ((Match->MchCod = Mch_GetParamMchCod ()) <= 0)
-      Lay_ShowErrorAndExit ("Code of match is missing.");
+      Lay_WrongMatchExit ();
    Mch_GetDataOfMatchByCod (Match);
 
    /***** Ensure parameters are correct *****/
    if (Game->GamCod != Match->GamCod)
-      Lay_ShowErrorAndExit ("Wrong game code.");
+      Lay_WrongGameExit ();
    if (Game->CrsCod != Gbl.Hierarchy.Crs.CrsCod)
-      Lay_ShowErrorAndExit ("Match does not belong to this course.");
+      Lay_WrongGameExit ();
 
    /***** Initialize context *****/
    Games->GamCod = Game->GamCod;
@@ -1624,8 +1624,8 @@ void Mch_CreateNewMatch (void)
 
    /***** Get form parameters *****/
    /* Get match code */
-   if ((GamCod = Gam_GetParamGameCod ()) == -1L)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+   if ((GamCod = Gam_GetParamGameCod ()) < 0)
+      Lay_WrongGameExit ();
 
    /* Get match title */
    Par_GetParToText ("Title",Title,Mch_MAX_BYTES_TITLE);
@@ -1830,7 +1830,7 @@ static void Mch_CreateIndexes (long GamCod,long MchCod)
 
       /* Get question code (row[0]) */
       if ((Question.QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-	 Lay_ShowErrorAndExit ("Wrong code of question.");
+	 Lay_WrongQuestionExit ();
 
       /* Get question index (row[1]) */
       if ((LongNum = Str_ConvertStrCodToLongCod (row[1])) < 0)
@@ -3921,7 +3921,7 @@ void Mch_GetMatchBeingPlayed (void)
 
    /***** Get match code ****/
    if ((MchCodBeingPlayed = Mch_GetParamMchCod ()) <= 0)
-      Lay_ShowErrorAndExit ("Code of match is missing.");
+      Lay_WrongMatchExit ();
 
    Mch_SetMchCodBeingPlayed (MchCodBeingPlayed);
   }
@@ -4314,11 +4314,11 @@ void Mch_GetMatchQuestionsFromDB (struct MchPrn_Print *Print)
 
       /* Get question code (row[0]) */
       if ((Print->PrintedQuestions[NumQst].QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-	 Lay_ShowErrorAndExit ("Wrong code of question.");
+	 Lay_WrongQuestionExit ();
 
       /* Get question index (row[1]) */
       if ((LongNum = Str_ConvertStrCodToLongCod (row[1])) < 0)
-	 Lay_ShowErrorAndExit ("Wrong code of question.");
+	 Lay_WrongQuestionExit ();
       QstInd = (unsigned) LongNum;
 
       /* Get indexes for this question (row[2]) */
diff --git a/swad_match_result.c b/swad_match_result.c
index d9f27a0a9..2d7e8f3a8 100644
--- a/swad_match_result.c
+++ b/swad_match_result.c
@@ -169,7 +169,7 @@ void MchRes_ShowMyMchResultsInGam (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Game begin *****/
@@ -219,9 +219,9 @@ void MchRes_ShowMyMchResultsInMch (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    if ((Match.MchCod = Mch_GetParamMchCod ()) <= 0)
-      Lay_ShowErrorAndExit ("Code of match is missing.");
+      Lay_WrongMatchExit ();
    Gam_GetDataOfGameByCod (&Game);
    Mch_GetDataOfMatchByCod (&Match);
 
@@ -373,7 +373,7 @@ void MchRes_ShowAllMchResultsInGam (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    Gam_GetDataOfGameByCod (&Game);
 
    /***** Game begin *****/
@@ -462,9 +462,9 @@ void MchRes_ShowAllMchResultsInMch (void)
 
    /***** Get parameters *****/
    if ((Game.GamCod = Gam_GetParams (&Games)) <= 0)
-      Lay_ShowErrorAndExit ("Code of game is missing.");
+      Lay_WrongGameExit ();
    if ((Match.MchCod = Mch_GetParamMchCod ()) <= 0)
-      Lay_ShowErrorAndExit ("Code of match is missing.");
+      Lay_WrongMatchExit ();
    Gam_GetDataOfGameByCod (&Game);
    Mch_GetDataOfMatchByCod (&Match);
 
@@ -883,7 +883,7 @@ static void MchRes_ShowMchResults (struct Gam_Games *Games,
 	 /* Get match code */
          MchPrn_ResetPrint (&Print);
 	 if ((Print.MchCod = DB_GetNextCode (mysql_res)) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of match.");
+	    Lay_WrongMatchExit ();
 
 	 /* Get match result data */
 	 Print.UsrCod = UsrDat->UsrCod;
diff --git a/swad_photo.c b/swad_photo.c
index 54516c1c9..24f749d99 100644
--- a/swad_photo.c
+++ b/swad_photo.c
@@ -2135,7 +2135,7 @@ static void Pho_ShowOrPrintClassPhotoDegrees (struct Pho_DegPhotos *DegPhotos,
 	{
 	 /***** Get next degree *****/
 	 if ((Deg.DegCod = DB_GetNextCode (mysql_res)) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of degree.");
+	    Lay_WrongDegreeExit ();
 
 	 /* Get data of degree */
 	 Deg_GetDataOfDegreeByCod (&Deg);
@@ -2232,7 +2232,7 @@ static void Pho_ShowOrPrintListDegrees (struct Pho_DegPhotos *DegPhotos,
 
 	 /* Get degree code (row[0]) */
 	 if ((Deg.DegCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of degree.");
+	    Lay_WrongDegreeExit ();
 
 	 /* Get data of degree */
 	 Deg_GetDataOfDegreeByCod (&Deg);
diff --git a/swad_survey.c b/swad_survey.c
index 2f47c2d8b..e9041ed1c 100644
--- a/swad_survey.c
+++ b/swad_survey.c
@@ -1282,7 +1282,7 @@ void Svy_GetDataOfSurveyByCod (struct Svy_Survey *Svy)
 
       /* Get survey scope (row[1]) */
       if ((Svy->Scope = Sco_GetScopeFromDBStr (row[1])) == Hie_Lvl_UNK)
-         Lay_ShowErrorAndExit ("Wrong survey scope.");
+         Lay_WrongScopeExit ();
 
       /* Get code of the country, institution, center, degree or course (row[2]) */
       Svy->Cod = Str_ConvertStrCodToLongCod (row[2]);
@@ -1320,7 +1320,7 @@ void Svy_GetDataOfSurveyByCod (struct Svy_Survey *Svy)
       switch (Svy->Scope)
         {
 	 case Hie_Lvl_UNK:	// Unknown
-            Lay_ShowErrorAndExit ("Wrong survey scope.");
+            Lay_WrongScopeExit ();
 	    break;
 	 case Hie_Lvl_SYS:	// System
             Svy->Status.IBelongToScope = Gbl.Usrs.Me.Logged;
@@ -2226,41 +2226,41 @@ void Svy_ReceiveFormSurvey (void)
      {
       case Hie_Lvl_SYS:
 	 if (Gbl.Usrs.Me.Role.Logged != Rol_SYS_ADM)
-	    Lay_ShowErrorAndExit ("Wrong survey scope.");
+	    Lay_WrongScopeExit ();
          NewSvy.Scope = Hie_Lvl_SYS;
          NewSvy.Cod = -1L;
          break;
       case Hie_Lvl_CTY:
 	 if (Gbl.Usrs.Me.Role.Logged != Rol_SYS_ADM)
-	    Lay_ShowErrorAndExit ("Wrong survey scope.");
+	    Lay_WrongScopeExit ();
 	 NewSvy.Scope = Hie_Lvl_CTY;
 	 NewSvy.Cod = Gbl.Hierarchy.Cty.CtyCod;
          break;
       case Hie_Lvl_INS:
 	 if (Gbl.Usrs.Me.Role.Logged != Rol_SYS_ADM &&
 	     Gbl.Usrs.Me.Role.Logged != Rol_INS_ADM)
-	    Lay_ShowErrorAndExit ("Wrong survey scope.");
+	    Lay_WrongScopeExit ();
 	 NewSvy.Scope = Hie_Lvl_INS;
 	 NewSvy.Cod = Gbl.Hierarchy.Ins.InsCod;
          break;
       case Hie_Lvl_CTR:
 	 if (Gbl.Usrs.Me.Role.Logged != Rol_SYS_ADM &&
 	     Gbl.Usrs.Me.Role.Logged != Rol_CTR_ADM)
-	    Lay_ShowErrorAndExit ("Wrong survey scope.");
+	    Lay_WrongScopeExit ();
 	 NewSvy.Scope = Hie_Lvl_CTR;
 	 NewSvy.Cod = Gbl.Hierarchy.Ctr.CtrCod;
          break;
       case Hie_Lvl_DEG:
 	 if (Gbl.Usrs.Me.Role.Logged != Rol_SYS_ADM &&
 	     Gbl.Usrs.Me.Role.Logged != Rol_DEG_ADM)
-	    Lay_ShowErrorAndExit ("Wrong survey scope.");
+	    Lay_WrongScopeExit ();
 	 NewSvy.Scope = Hie_Lvl_DEG;
 	 NewSvy.Cod = Gbl.Hierarchy.Deg.DegCod;
          break;
       case Hie_Lvl_CRS:
 	 if (Gbl.Usrs.Me.Role.Logged != Rol_SYS_ADM &&
 	     Gbl.Usrs.Me.Role.Logged != Rol_TCH)
-	    Lay_ShowErrorAndExit ("Wrong survey scope.");
+	    Lay_WrongScopeExit ();
 	 NewSvy.Scope = Hie_Lvl_CRS;
 	 NewSvy.Cod = Gbl.Hierarchy.Crs.CrsCod;
          break;
@@ -3700,7 +3700,7 @@ void Svy_RequestRemoveQst (void)
 
    /* Get question code */
    if ((SvyQst.QstCod = Svy_GetParamQstCod ()) < 0)
-      Lay_ShowErrorAndExit ("Wrong code of question.");
+      Lay_WrongQuestionExit ();
 
    /* Get question index */
    SvyQst.QstInd = Svy_GetQstIndFromQstCod (SvyQst.QstCod);
@@ -3742,7 +3742,7 @@ void Svy_RemoveQst (void)
 
    /* Get question code */
    if ((SvyQst.QstCod = Svy_GetParamQstCod ()) < 0)
-      Lay_ShowErrorAndExit ("Wrong code of question.");
+      Lay_WrongQuestionExit ();
 
    /* Get question index */
    SvyQst.QstInd = Svy_GetQstIndFromQstCod (SvyQst.QstCod);
@@ -3757,7 +3757,7 @@ void Svy_RemoveQst (void)
 		   " WHERE QstCod=%ld",
 		   SvyQst.QstCod);
    if (!mysql_affected_rows (&Gbl.mysql))
-      Lay_ShowErrorAndExit ("The question to be removed does not exist.");
+      Lay_WrongQuestionExit ();
 
    /* Change index of questions greater than this */
    DB_QueryUPDATE ("can not update indexes of questions",
@@ -3844,7 +3844,7 @@ static void Svy_ReceiveAndStoreUserAnswersToASurvey (long SvyCod)
         {
          /* Get next question */
          if ((QstCod = DB_GetNextCode (mysql_res)) <= 0)
-            Lay_ShowErrorAndExit ("Error: wrong question code.");
+            Lay_WrongQuestionExit ();
 
          /* Get possible parameter with the user's answer */
          snprintf (ParamName,sizeof (ParamName),"Ans%010u",(unsigned) QstCod);
diff --git a/swad_test.c b/swad_test.c
index 7cf651cab..69f7fc3eb 100644
--- a/swad_test.c
+++ b/swad_test.c
@@ -2169,7 +2169,7 @@ static void Tst_ListOneOrMoreQuestionsForEdition (struct Tst_Test *Test,
       /***** Get question code (row[0]) *****/
       row = mysql_fetch_row (mysql_res);
       if ((Test->Question.QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of question.");
+         Lay_WrongQuestionExit ();
 
       /***** Write question row *****/
       Tst_WriteQuestionListing (Test,NumQst);
@@ -2432,7 +2432,7 @@ static void Tst_ListOneOrMoreQuestionsForSelectionForSet (struct Exa_Exams *Exam
       /* Get question code (row[0]) */
       row = mysql_fetch_row (mysql_res);
       if ((Question.QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of question.");
+         Lay_WrongQuestionExit ();
 
       /* Write question row */
       Tst_WriteQuestionRowForSelection (NumQst,&Question);
@@ -2517,7 +2517,7 @@ static void Tst_ListOneOrMoreQuestionsForSelectionForGame (struct Gam_Games *Gam
       /* Get question code (row[0]) */
       row = mysql_fetch_row (mysql_res);
       if ((Question.QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-         Lay_ShowErrorAndExit ("Wrong code of question.");
+         Lay_WrongQuestionExit ();
 
       /* Write question row */
       Tst_WriteQuestionRowForSelection (NumQst,&Question);
@@ -3148,7 +3148,7 @@ unsigned Tst_CountNumQuestionsInList (const char *ListQuestions)
      {
       Par_GetNextStrUntilSeparParamMult (&Ptr,LongStr,Cns_MAX_DECIMAL_DIGITS_LONG);
       if (sscanf (LongStr,"%ld",&QstCod) != 1)
-         Lay_ShowErrorAndExit ("Wrong question code.");
+         Lay_WrongQuestionExit ();
       NumQuestions++;
      }
    return NumQuestions;
@@ -4530,7 +4530,7 @@ bool Tst_CheckIfQuestionExistsInDB (struct Tst_Question *Question)
         {
 	 /* Get question code */
          if ((Question->QstCod = DB_GetNextCode (mysql_res_qst)) < 0)
-            Lay_ShowErrorAndExit ("Wrong code of question.");
+            Lay_WrongQuestionExit ();
 
          /* Get answers from this question */
          NumOptsExistingQstInDB =
@@ -4714,7 +4714,7 @@ void Tst_RemoveSelectedQsts (void)
 	 /* Get question code (row[0]) */
 	 row = mysql_fetch_row (mysql_res);
 	 if ((QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of question.");
+	    Lay_WrongQuestionExit ();
 
 	 /* Remove test question from database */
 	 Tst_RemoveOneQstFromDB (Gbl.Hierarchy.Crs.CrsCod,QstCod);
@@ -4759,7 +4759,7 @@ void Tst_RequestRemoveOneQst (void)
    /* Get the question code */
    Test.Question.QstCod = Tst_GetParamQstCod ();
    if (Test.Question.QstCod <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of question.");
+      Lay_WrongQuestionExit ();
 
    /* Get a parameter that indicates whether it's necessary
       to continue listing the rest of questions */
@@ -4820,7 +4820,7 @@ void Tst_RemoveOneQst (void)
    /***** Get the question code *****/
    QstCod = Tst_GetParamQstCod ();
    if (QstCod <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of question.");
+      Lay_WrongQuestionExit ();
 
    /***** Get a parameter that indicates whether it's necessary
           to continue listing the rest of questions ******/
@@ -4862,7 +4862,7 @@ static void Tst_RemoveOneQstFromDB (long CrsCod,long QstCod)
 		   CrsCod);
 
    if (!mysql_affected_rows (&Gbl.mysql))
-      Lay_ShowErrorAndExit ("Wrong question.");
+      Lay_WrongQuestionExit ();
   }
 
 /*****************************************************************************/
@@ -4883,7 +4883,7 @@ void Tst_ChangeShuffleQst (void)
    /***** Get the question code *****/
    Test.Question.QstCod = Tst_GetParamQstCod ();
    if (Test.Question.QstCod <= 0)
-      Lay_ShowErrorAndExit ("Wrong code of question.");
+      Lay_WrongQuestionExit ();
 
    /***** Get a parameter that indicates whether it's necessary to continue listing the rest of questions ******/
    EditingOnlyThisQst = Par_GetParToBool ("OnlyThisQst");
diff --git a/swad_test_print.c b/swad_test_print.c
index 7b67647f5..a7d1db6a0 100644
--- a/swad_test_print.c
+++ b/swad_test_print.c
@@ -309,7 +309,7 @@ void TstPrn_ShowTestPrintToFillIt (struct TstPrn_Print *Print,
 
 	 /* Show question */
 	 if (!Tst_GetQstDataFromDB (&Question))	// Question exists
-	    Lay_ShowErrorAndExit ("Wrong question.");
+	    Lay_WrongQuestionExit ();
 
 	 /* Write question and answers */
 	 TstPrn_WriteQstAndAnsToFill (&Print->PrintedQuestions[NumQst],NumQst,&Question);
@@ -2782,7 +2782,7 @@ void TstPrn_GetPrintQuestionsFromDB (struct TstPrn_Print *Print)
 
 	 /* Get question code (row[0]) */
 	 if ((Print->PrintedQuestions[NumQst].QstCod = Str_ConvertStrCodToLongCod (row[0])) < 0)
-	    Lay_ShowErrorAndExit ("Wrong code of question.");
+	    Lay_WrongQuestionExit ();
 
 	 /* Get score (row[1]) */
 	 Str_SetDecimalPointToUS ();	// To get the decimal point as a dot