I am seeing this issue as well.  We recently switched from Infragistics20.WebUI.UltraWebGrid.v8.2 to Infragistics35.WebUI.UltraWebGrid.v8.3 and that's the first time I saw the error (I checked back through recent changes in our code and nothing seems to be present other than the IG revision change). 

As for a code snippet, previously, I had the following in an ajax clicked event

protected [click event from aspx](object sender, eventargs e) {

grid.Columns.Clear();
grid.DataSource = GetDataSource();
grid.DataBind(); <-- error points here (error attached at bottom)

}

where GetDataSource() performs a lookup and "filters" out columns based on the criteria related to the aspx click event.

I have subsequently tried adding the following prior to the datasource change with no success.

grid.ResetBands();
grid.ResetColumns();
grid.ResetRows();

We are using the OutlookGroupBy and its a rather customized grid.  Any thoughts you might have would be greatly appreciated,

Adam

Error:

[NullReferenceException: Object reference not set to an instance of an object.]
   Infragistics.WebUI.UltraWebGrid.GroupByColumnComparer.Compare(Object x, Object y) +150
   System.Array.BinarySearch(Array array, Int32 index, Int32 length, Object value, IComparer comparer) +215

[InvalidOperationException: Failed to compare two elements in the array.]
   System.Array.BinarySearch(Array array, Int32 index, Int32 length, Object value, IComparer comparer) +276
   System.Collections.SortedList.IndexOfKey(Object key) +28
   System.Collections.SortedList.get_Item(Object key) +12
   Infragistics.WebUI.UltraWebGrid.UltraGridLayout.RegisterGroupByColumn(UltraGridColumn groupedColumn) +23
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.GroupRows(RowsCollection rows, UltraGridColumn column) +263
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.SortGroupRows(RowsCollection rows) +330
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.PerformGroupRows() +216
   Infragistics.WebUI.UltraWebGrid.DBBinding.BindList(IEnumerable datasource) +1336
   Infragistics.WebUI.UltraWebGrid.DBBinding.DataBind(Object dataSource, String dataMember) +1089
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.DataBind() +397

Hi Adam,

I am seeing the same issue as you did. Below is the code where I am getting the error.  
public void RebindGrid(bool refreshData, bool resetGrid)
{ 
this.DataSet = null;
this.TheGrid.Clear();
this.TheGrid.Bands.Clear();
this.TheGrid.DataBind();  -- I get the same error you mentioned in your post here
}

When I try to Rebind the grid after grouping on two columns I am getting this error. Before Rebinding the grid I am doing grid.Clear(); I tried adding the following code before the Databind() but was of no use.

grid.ResetBands();
grid.ResetColumns();
grid.ResetRows();

The ViewType is set to OutlookGroupBy and it is customized as well. If you have solved this issue would you please let me know how you did it. I would appreciate it.

I would be very thankful to anybody who could help to solve this issue. Thanks.

-Bhargavi R.

Error:

[NullReferenceException: Object reference not set to an instance of an object.]
   Infragistics.WebUI.UltraWebGrid.GroupByColumnComparer.Compare(Object x, Object y) +252
   System.Array.BinarySearch(Array array, Int32 index, Int32 length, Object value, IComparer comparer) +229

[InvalidOperationException: Failed to compare two elements in the array.]
   System.Array.BinarySearch(Array array, Int32 index, Int32 length, Object value, IComparer comparer) +289
   System.Collections.SortedList.IndexOfKey(Object key) +31
   System.Collections.SortedList.get_Item(Object key) +15
   Infragistics.WebUI.UltraWebGrid.UltraGridLayout.RegisterGroupByColumn(UltraGridColumn groupedColumn) +65
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.GroupRows(RowsCollection rows, UltraGridColumn column) +410
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.SortGroupRows(RowsCollection rows) +449
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.PerformGroupRows() +323
   Infragistics.WebUI.UltraWebGrid.DBBinding.BindList(IEnumerable datasource) +3711
   Infragistics.WebUI.UltraWebGrid.DBBinding.DataBind(Object dataSource, String dataMember) +2019
   Infragistics.WebUI.UltraWebGrid.UltraWebGrid.DataBind() +683

Thank you,
Bhargavi R.

This works for me:

before binding:    

uwgReport.ExpandAll(false);

        foreach (UltraGridColumn col in uwgReport.Columns)

        {

            col.IsGroupByColumn = false; //mandatory because of infragistics bug

        }

  uwgReport.Columns.Clear();

manu