I know this problem has been discussed extensively, but I can't fix it even after reading the previous posts. I have an institutional email address that uses outlook.office365 server and mandatory two factor autentication. I had my Thunderbird setup with this, which suddenly stopped working one day on my office PC. I updated Thunderbird to the newest version, but the issue pertains. Currently I'm running Thunderbird 115.12.2. on a Windows 10 machine. When I try to fetch my emails from this server, a popup window appears that asks for my institutional login credentials. When I enter them, a second window appears, asking for the two factor autentication. However, this window seems to be corrupt, as it does not contain any information, and and it's impossible to type in verification code, as there's no input area at all (see the first picture - note that I'm using a localized version of Thunderbird). When I click on Privacy and cookies in the right bottom corner, then two lines appear (although without any labels), where I can type in my verification code (I guess that it is the second line, because it shows dots in place of the typed characters, as for passwords). A screenshot of this window can be seen in the second picture. However, after typing the correct code and clicking on the grey button, the first window reappears, this time with my email address that keeps flashing forever and nothing happens. It does not even matter if I type in the right verification number or just anything, it produces the same behaviour. As a result, I can't log in to my mailbox, which is operational, because I can log in there through the web interface of outlook, and also from my laptop using Thunderbird 78.14.0. I also made sure that the server name and authentication methods are correct (outlook.office365.com, port 993, SSL/TLS, OAuth2). Do you have any suggestion how to solve this issue? Many thanks.