We just upgraded ext.net version from 3.2.0 to 4.8.3. After this upgrade we encountered a problem, both in Chrome and IE 11.

The view has a GridPanel that is filtered by three dropdowns. At some point the filter throws the following error on ext.axd script file:

'Unable to get property 'apply' of undefined or null reference'.


After some tests we found out that the error was thrown by the PrepareToolbar function used in one of the columns of the grid. We changed that, and now we are using PrepareCommand. The error is fixed in Chrome but persists in IE. Whenever we execute the code in debug mode, IE and Visual Studio both crash.


Thanks in advance!