Multiple controls with the same ID '_LightweightGroupPlaceHolder' were found

[Ben]

Hi Everyone,

 I upgraded to ASP.NET AJAX 2016 Q1 today, and I've been receiving this error once in awhile.  I'm not sure exactly what causes it.

 I don't see it list any of my code.  It does only occur on one page (so far).  In this page I do two things related to grouping.  In the 'DetailTableDataBind' event I group by a specific field:

                e.DetailTableView.GroupByExpressions.Clear();
                var gridGroupByExpression = new GridGroupByExpression();
                gridGroupByExpression.GroupByFields.Add(new GridGroupByField { FieldName = "FIELD NAME", SortOrder = GridSortOrder.Descending });
                gridGroupByExpression.SelectFields.Add(new GridGroupByField { FieldName = "FIELD NAME", HeaderText = "HEADER TEXT", Aggregate = GridAggregateFunction.Avg, FormatString = "{0:0}" });
                gridGroupByExpression.SelectFields.Add(new GridGroupByField { FieldName = "FIELD NAME", HeaderText = "HEADER TEXT", Aggregate = GridAggregateFunction.Avg });
                e.DetailTableView.GroupByExpressions.Add(gridGroupByExpression);

 And in the 'GroupsChanging' event, I disable paging if at least one column is being grouped by:

(sender as RadGrid).AllowPaging = !(e.Action != GridGroupsChangingAction.Ungroup || e.TableView.GroupByExpressions.Count > 1);

 

Here's the full exception:

 System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.Web.HttpException (0x80004005): Multiple controls with the same ID '_LightweightGroupPlaceHolder' were found. FindControl requires that controls have unique IDs.
    at System.Web.UI.Control.FillNamedControlsTable(Control namingContainer, ControlCollection controls)
    at System.Web.UI.Control.FindControl(String id, Int32 pathOffset)
    at Telerik.Web.UI.GridGroupPanel.AddLightweightGroups(GridTableView tableView, Int32 level, Int32& tableIndex)
    at Telerik.Web.UI.GridGroupPanel.InitializeIn(RadGrid grid, Boolean FromViewState)
    at Telerik.Web.UI.RadGrid.CreateGroupPanel(Control container)
    at Telerik.Web.UI.RadGrid.CreateChildControls(IEnumerable dataSource, Boolean dataBinding)
    at System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls()
    at System.Web.UI.Control.EnsureChildControls()
    at Telerik.Web.UI.GridBaseDataList.get_Controls()
    at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState)
    at System.Web.UI.Control.LoadViewStateRecursive(Object savedState)
    at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState)
    at System.Web.UI.Control.LoadViewStateRecursive(Object savedState)
    at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState)
    at System.Web.UI.Control.LoadViewStateRecursive(Object savedState)
    at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState)
    at System.Web.UI.Control.LoadViewStateRecursive(Object savedState)
    at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState)
    at System.Web.UI.Control.LoadViewStateRecursive(Object savedState)
    at System.Web.UI.Page.LoadAllState()
    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
    at System.Web.UI.Page.HandleError(Exception e)
    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
    at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
    at System.Web.UI.Page.ProcessRequest()
    at System.Web.UI.Page.ProcessRequest(HttpContext context)
    at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
    at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

[Pavlina]

Hello,

Try setting different UniqueName for the columns in RadGrid and see if it is helpful.

 

Regards,
Pavlina
Telerik

[Richard Watson]

Hi Pavlina,

 Thanks for the reply.  This RadGrid does already have different UniqueNames for each column.  It does have a detail table, however, where some of the columns from the DetailTable also share UniqueNames with the main RadGrid.

 I changed these as well just to be safe, so every UniqueName from the RadGrid and DetailTable columns are unique, but I am still experiencing this error once every 10,000 pageviews or so.

 This only started happening once I upgraded to Telerik ASP.NET AJAX 2016 Q1.

 Just today I tried upgrading to the new 'Latest Internal Build' 'Telerik_UI_for_ASP.NET_AJAX_2016_1_127_Dev_hotfix'.  However, I am still experiencing this issue.

 Has anyone else come across this issue?  Or do you perhaps have any other ideas as to why this would happen?

[Richard Watson]

Just an  FYI I found how to reproduce the error, and I've submitted a bug report ticket

 It only applies to a RadGrid with a detail table in Lightweight rendering, and may only apply to Master pages

 Load the page -> Expand a 'Detail' table -> Group by a column in the Detail table -> Group by a column in the Master table -> Try to expand another 'Detail' table - triggers exception

[Pavlina]

Hi Richard,

Lets continue our communication in the support ticket you have opened in order to avoid duplicate posts.

Regards,
Pavlina
Telerik