diff --git a/calendar/js/app.js b/calendar/js/app.js
index 64ed6f2b41..3d7a2c0469 100644
--- a/calendar/js/app.js
+++ b/calendar/js/app.js
@@ -3567,8 +3567,13 @@ var CalendarApp = /** @class */ (function (_super) {
                 account_id: egw.user('account_id'),
                 email: egw.user('account_email'),
                 cal_id: _data.id
-            }, _data.start, _data.end], function (_url) {
-            app.status.openCall(_url);
+            }, _data.start, _data.end], function (_value) {
+            if (_value) {
+                if (_value.err)
+                    egw.message(_value.err, 'error');
+                if (_value.url)
+                    app.status.openCall(_value.url);
+            }
         }).sendRequest();
     };
     /**
diff --git a/calendar/js/app.ts b/calendar/js/app.ts
index 5671f20970..4a30f4af33 100644
--- a/calendar/js/app.ts
+++ b/calendar/js/app.ts
@@ -4428,8 +4428,12 @@ class CalendarApp extends EgwApp
 					account_id:egw.user('account_id'),
 					email:egw.user('account_email'),
 					cal_id:_data.id
-				}, _data.start, _data.end], function(_url){
-				app.status.openCall(_url);
+				}, _data.start, _data.end], function(_value){
+					if (_value)
+					{
+						if (_value.err) egw.message(_value.err, 'error');
+						if(_value.url) app.status.openCall(_value.url);
+					}
 			}).sendRequest();
 	}
 }