Avast is blocking Firefox sync

[REDACTED]

Steps to reproduce:

- make a fresh intall of Firefox with Avast installed
- log in to your Firefox sync account with your email and password
- you can wait or force a manual sync
- nothing will happen
- you can check errors at: about:sync-log - especially "TokenServerClientNetworkError"

- close Firefox
- turn off Avast for 10 minutes
- start Firefox
- choose manual sync
- it will sync all your bookmarks, extensions, etc.

Tested with newest Avast, Win 10 64bit, Firefox 41 beta

[REDACTED]

Ok, found out that it is a much complex problem. Some https sites also doesn't work with sec_error_bad_signature or  ssl_error_bad_mac_read errors.

The solution is here: https://support.mozilla.org/hu/questions/1075167 - in short: Uncheck the "Enable HTTPS Scanning" option in Avast.