Outlook.com accounts not working in Thunderbird – intermittent OAuth2 login errors
I am using Thunderbird 149.0 (64‑bit) on Windows 11 25H2. Recently, Thunderbird has started showing error messages for my Outlook.com accounts every time the program star… (lue lisää)
I am using Thunderbird 149.0 (64‑bit) on Windows 11 25H2.
Recently, Thunderbird has started showing error messages for my Outlook.com accounts every time the program starts. Sign‑in fails, and sometimes an additional error appears: Error code 12.
I have three Outlook.com accounts in Thunderbird. All of them use the IMAP server: outlook.office365.com.
When I open and close Thunderbird several times, the login eventually succeeds at random. After that, Thunderbird re-downloads all emails from the server, which suggests that the OAuth2 token is not updating correctly. All accounts are using OAuth2 authentication. One suggestion was to switch to the App Password method, because Outlook.com OAuth2 is said to be unstable in third‑party applications. Question: Is the App Password method less secure than OAuth2, and is it advisable to switch to it for Outlook.com accounts in Thunderbird or something else what i can do?