I have a content page that has a master page.  I have an updatepanel and a scriptmanger in my content page.  I defined a handler for OnPageError for the scriptmanager and defined a error template for the scriptmanager but when I set the e.errormessage in the OnPageError event, but if I set a break point in the event, the break point is never reached and the error message in the template still displays 'unknown error'  Any ideas?

if I put a button on the page and in the click event of the button i manually throw and error.

throw new Exception("error button clicked");

the event fires and works fine.

 

but if I put some invalid characters like '<img src' inside a textbox and then click the button (removing the throw) then the OnPageError isn't fired