I have faced this before so I can give you multiple solutions on this exception. Please refer below solutions for you.
Easiest way to fix it by simply adding the empty event as shown below
protected void mygrd_RowDeleting(object mysender, GridViewDeleteEventArgs mye)
If above solution is not working for you then you can try below solution
If the gridview binding is in the pageload. Then I guess this may be the cause of the issue. So you need to just move your GV binding as shown below
Within your Page_Load Method
Hope the solutions helped you.