Incorrect file signature when updating Avast Business Security. How to fix?

Question

Windows

I installed Avast Business Security version 11.2.25.11 on the enterprise, on a machine with Windows 7 pro , a network on a domain with two proxies, authorization on a proxy in Avast was registered.
The problem is the following, the antivirus is not updated (although there is a connection), but reports that "The file signature is not correct. The installation will be interrupted."
I googled this question, on the off forum there are two branches on this topic, like 2010 and 2011. Both solutions from there did not solve the problem in my situation.
What I did: Reinstalled, Reinstalled through the "Uninstall Programs" control panel, Kaspersky went through the computer (found some kind of nonsense), Checked Avast at boot (similarly). I downloaded updates from the site, the antivirus updated the database, but again it does not download updates via the Internet.

Answer 1

and uninstall and reinstall from the online installer?
Did you register authorization on the second proxy too?
is traffic interception worth it?