diff --git a/NEWS b/NEWS
index 54aea6cc0..4bc22406a 100644
--- a/NEWS
+++ b/NEWS
@@ -30,6 +30,7 @@ Bug fixes
  - fixed contextual menu of the current calendar view (#2557)
  - fixed handling of the '=' character in cards/events/tasks (#2505)
  - simplify searches in the address book (#2187)
+ - warn user when dnd failed because of a resource conflict (#1613)
 
 2.1.1b (2013-12-04)
 -------------------
diff --git a/UI/Scheduler/UIxAppointmentActions.m b/UI/Scheduler/UIxAppointmentActions.m
index 08d6c9f9c..db6d55c91 100644
--- a/UI/Scheduler/UIxAppointmentActions.m
+++ b/UI/Scheduler/UIxAppointmentActions.m
@@ -1,6 +1,6 @@
 /* UIxAppointmentActions.m - this file is part of SOGo
  *
- * Copyright (C) 2011 Inverse inc.
+ * Copyright (C) 2011-2014 Inverse inc.
  *
  * Author: Wolfgang Sourdeau <wsourdeau@inverse.ca>
  *
@@ -21,6 +21,7 @@
  */
 
 #import <Foundation/NSCalendarDate.h>
+#import <Foundation/NSDictionary.h>
 #import <Foundation/NSString.h>
 
 #import <NGObjWeb/NSException+HTTP.h>
@@ -33,6 +34,7 @@
 #import <NGCards/iCalEvent.h>
 
 #import <SOGo/NSCalendarDate+SOGo.h>
+#import <SOGo/NSDictionary+Utilities.h>
 #import <SOGo/SOGoUser.h>
 #import <SOGo/SOGoUserDefaults.h>
 #import <Appointments/iCalEvent+SOGo.h>
@@ -56,6 +58,7 @@
   SOGoUserDefaults *ud;
   NSString *daysDelta, *startDelta, *durationDelta;
   NSTimeZone *tz;
+  NSException *ex;
 
   rq = [context request];
 
@@ -105,16 +108,24 @@
 	[event updateRecurrenceRulesUntilDate: end];
 
       [event setLastModified: [NSCalendarDate calendarDate]];
-      [co saveComponent: event];
-
-      response = [self responseWith204];
+      ex = [co saveComponent: event];
+      if (ex)
+        {
+          NSDictionary *jsonResponse;
+          jsonResponse = [NSDictionary dictionaryWithObjectsAndKeys:
+                                       [ex reason], @"message",
+                                       nil];
+          response = [self responseWithStatus: 403
+                                    andString: [jsonResponse jsonRepresentation]];
+        }
+      else
+        response = [self responseWith204];
     }
   else
     response
       = (WOResponse *) [NSException exceptionWithHTTPStatus: 400
                                                      reason: @"missing 'days', 'start' and/or 'duration' parameters"];
 
-    
   return response;
 }
 
diff --git a/UI/WebServerResources/SchedulerUI.js b/UI/WebServerResources/SchedulerUI.js
index 81b8e5928..725345d61 100644
--- a/UI/WebServerResources/SchedulerUI.js
+++ b/UI/WebServerResources/SchedulerUI.js
@@ -135,6 +135,10 @@ function updateEventFromDraggingCallback(http) {
         if (isHttpStatus204(http.status)) {
             refreshEventsAndDisplay();
         }
+        else {
+            var response = http.responseText.evalJSON(true);
+            showAlertDialog(response['message']);
+        }
     }
 }