From Customer Support: In the current implementation there is a problem when the EditType is set to Row and the OnBatchEditOpening event is canceled. The problem is caused by the fact that when the row closes the grid will still try to obtain the values from the cells that were not opened for edit and this causes a JavaScript error.
This is definitely an issue. My current workaround is either to use Cell Edit mode (which is undesirable) or to completely do away with the type of editing that was advertised with the RadGrid. A workaround to extend/update the code that is broken would be really useful.