I'm facing a low occurrence null reference exception accessing SellectedCells[] in a high volume WebDataGrid. The code is executed several hundred times a day, but I get 3-4 exceptions a week and I cannot determine why. I've added some explicit null checks to isolate what object is null and that only adds to the confusion. The WebDataGrid is bound to a basic DataSet and it is not possible for any "cell" in the DataSet to be empty much less null. I'm getting null reference exceptions on x=0 and x=1/2/6/etc. I cannot force duplicate this no matter how much I try so I have the following code added to trap/log occurrences as they happen in the production environment.

if (WebDataGridWaves.Behaviors.Selection.SelectedCells.Count != 0)

{

for (int x = 0; x < WebDataGridWaves.Behaviors.Selection.SelectedCells.Count; x++)

{

// Debug data for NullReferenceException accessing WebDataGridWaves

try

{

if (WebDataGridWaves.Behaviors.Selection.SelectedCells[x] == null)

{

Common.LogEvent("Error", "DeployConvergenceApplicationBySite", "SelectedCells[x] is null\r\n\r\nSite = " + sSite + "\r\nWebDataGridWaves.Behaviors.Selection.SelectedCells.Count = " + WebDataGridWaves.Behaviors.Selection.SelectedCells.Count.ToString() + "\r\nx = " + x.ToString());

}

else

{

if (String.IsNullOrEmpty(WebDataGridWaves.Behaviors.Selection.SelectedCells[x].Text))

{

Common.LogEvent("Error", "DeployConvergenceApplicationBySite", "SelectedCells[x].Text is NullOrEmpty\r\n\r\nSite = " + sSite + "\r\nWebDataGridWaves.Behaviors.Selection.SelectedCells.Count = " + WebDataGridWaves.Behaviors.Selection.SelectedCells.Count.ToString() + "\r\nx = " + x.ToString());

}

else

{

string sTemp = WebDataGridWaves.Behaviors.Selection.SelectedCells[x].Text;

}

}

}

catch (Exception ex)

{

Common.LogEvent("Error", "DeployConvergenceApplicationBySite", "Message:\r\n" + ex.Message + "\r\nStackTrace:\r\n" + ex.StackTrace + "\r\n\r\nSite = " + sSite + "\r\nWebDataGridWaves.Behaviors.Selection.SelectedCells.Count = " + WebDataGridWaves.Behaviors.Selection.SelectedCells.Count.ToString() + "\r\nx = " + x.ToString());

}

}

}

Here are some of the examples being logged:

Exception in DeployConvergenceApplicationBySite

SelectedCells[x] is null

Site = CTI_pl_bhw

WebDataGridWaves.Behaviors.Selection.SelectedCells.Count = 11

x = 6

Exception in DeployConvergenceApplicationBySite

SelectedCells[x] is null

Site = MEX

WebDataGridWaves.Behaviors.Selection.SelectedCells.Count = 10

x = 2

Exception in DeployConvergenceApplicationBySite

SelectedCells[x] is null

Site = KR

WebDataGridWaves.Behaviors.Selection.SelectedCells.Count = 4

x = 0

Any suggestions on why a SellectedCell[x] would be null when Count > x ?