How to prevent full page postback on selectedindexchange for dropdownlist

Answer 1

your code seems fine. did you try to comment out asp:Panel tab? if you unccoment triggers, you need to put asp:UpdatePanel around gridview

Answer 2

As per this post it looks like your asp:Panel could be the culprit with the ClientIDMode="Static". Try changing this so it inherits.

Answer 3

You'd need to specify ChildrenAsTriggers="true" in your UpdatePanel tag. The error you're getting is because your dropdown doesn't physically exist in the markup, which is what a Trigger line expects to find during compliation/runtime - instead, you are adding it dynamically as a control in your RowCreated function. It might be possible to, in that same function, add a trigger to the UpdatePanel dynamically, if you wanted to try that, instead.