in the attached file you see the exception I get (Sorry, it's in German). The Problem with this exception is, that it appears not every time by doing the same steps. So we can't say definititly what step let this exception occures.
So here are the circumstances:
- RadGradView with some columns (4-5)
- Binding on a DataTable
- ReadOnly = false
So when from a dialog a value is puttin' in one of the cells, the problem somtimes appears.
I downloaded the source code and searched a bit. (In GridView_WPF.sln: GridView/Cells/GridViewCell.cs)
In the method 'PrepareCellToolTip' the second time when ToolTipService.GetToolTip is called:
var visualElementToolTip = ToolTipService.GetToolTip(
ar isCellErrorToolTip =
.CellErrorMessage == visualElementToolTip;
var row =
var rowToolTip = ToolTipService.GetToolTip(row) ?? string
Before row is hand over to 'GetToolTip()', there should be proved if it isn't null, right?