InnerException = {"The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>)."}

since you did not posted your code,We cannot exactly say what to do , but generally for such error You need to use <# instead of <= or <%# instead of <%= in your page

Check this
http://stackoverflow.com/questions/778952/the-controls-collection-cannot-be-modified-because-the-control-contains-code-bl[^]

http://stackoverflow.com/questions/18097931/the-controls-collection-cannot-be-modified-because-the-control-contains-code-blo[^]