I didn't upgrade to Ubuntu 20.10 at all Olivier, I'm still on Ubuntu Mate 20.04.1. Maybe it came with an update? Thunderbird already was a longer time just in English. But as far I know the problem started 27th October, yes indeed.
Maybe also nice to know, when I didn't close the window displaying the error, I got notification of received new mails.
I didn't upgrade to Ubuntu 20.10 at all Olivier, I'm still on Ubuntu Mate 20.04.1. Maybe it came with an update? Thunderbird already was a longer time just in English. But as far I know the problem started 27th October, yes indeed.
Maybe also nice to know, when I didn't close the window displaying the error, I got notification of received new mails.