Fix for Issue 2473 Add-PnPSiteDesignTask

Commands/SiteDesigns/AddSiteDesignTask.cs

@@ -49,7 +49,26 @@ protected override void ExecuteCmdlet()
                         ThrowTerminatingError(new ErrorRecord(new System.Exception("Invalid URL"), "INVALIDURL", ErrorCategory.InvalidArgument, WebUrl));
                     }
                 }
-                Tenant.AddSiteDesignTask(tenantContext, webUrl, SiteDesignId.Id);
+                try
+                {
+                    var designTask = Tenant.AddSiteDesignTask( tenantContext, webUrl, SiteDesignId.Id );
+                    tenantContext.Load( designTask );
+                    tenantContext.ExecuteQueryRetry();
+                    WriteObject( designTask );
+                }
+                catch (System.Net.WebException ex)
+                {
+                    if (ex.Status == System.Net.WebExceptionStatus.ProtocolError)
+                    {
+                        var webResponse = ex.Response as System.Net.HttpWebResponse;
+                        if (null != webResponse && 
+                            webResponse.StatusCode == System.Net.HttpStatusCode.Forbidden)
+                        {
+                            WriteObject( "The server threw an exception (see below). It seems you may not have access to the server or you are executing this script outside of the tenant admin URL eg. yourtenant-admin.sharepoint.com. Please Connect to the tenant URL first and try again." );
+                        }
+                    }
+                    WriteObject( ex );
+                }
             }
         }
     }