ASP.NET AJAX GridView + UpdatePanel Async error on postback
Whenever this type of error is there, you can define function asyncpostbackerror in scriptmanager to debug to the real problem.
In my case, I put the GridView and gave the command “Edit” to the gridview custom button. But as Edit is inbuild command, we need to define “RowEditing” function. But that was not define and due to that it throws AsyncError. Debugged using asyncpostbackerror and found the issue.
It is cool when you have better error handling so that can find errors quickly.