Hi,
Currently, Q&A only support topics listed in the home page from below link:
https://learn.microsoft.com/en-us/answers/products/
Since then, I would direct you to following forum for assistance:
https://forums.asp.net/1022.aspx/1?ASP+NET+AJAX+Ajax+Control+Toolkit+ACT+
Reference thread:Ajaxcontroltoolkit suddenly stop working at server
https://forums.asp.net/t/2137177.aspx?Ajaxcontroltoolkit+suddenly+stop+working+at+server+
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Hope this helps and please help to accept as Answer if the response is useful.
Thanks,
Jenny