An update of Thunderbird (1:78.10.0-1) to 1:78.11.0-1 yesterday seems to have broken it. It says:
Authentication failure while connecting to server imap.gmail.com
I though maybe that Google's strict security didn't recognise the new version so I tried resetting third party app access, but that just got me an error message:
NS-ERROR-NET-INADEQUATE-SECURITY
Thunderbird seems to have had this issue before and a previous fix worked for me.
There are bug reports already here and here and here. The same fix has been noted here.
I am not sure if the fix:
network.http.spdy.enabled.http2 = false
introduces any security risk.
