Httpexception The Controls collection cannot be modified because the control contains code blocks

Question

I try to add a user control by ajax but I have The same problem of This One, and the suggested solution is Remove <%= From head of page, but my master page is:

As you see there is not any <%= character in head of page, So where is the problem? why I get the error yet?

any suggestion?

Answer 1

I put target elements in Panel or placeholder, and there is not any more error.