Looks like an interfering security app, as outlook.com accounts work fine in 115 (with OAuth2 authentication).

What's the antivirus?

No antivirus was installed. It worked good, the problem occurs after upgraded to 115.0.1 today.

If I receive a message with that link http://account.live.com/ and click it, it opens the settings page for my MS account. There is no error message like the one you showed.

How did you update TB, and where did you download it?

The TB popped up a message that a new update is available, need to download to update. I clicked the link and downloaded the TB, then installed over the existing TB. Launching the new TB, all my outlook accounts required me to sign in one by one, the warining came up after sign in. I have tried to uninstall TB, download a new package and reinstall it, also tried to remove the account and add it back, the warning is the same. There is no problem to access my outlook account through browser. any idea? Thanks.

TB would only initiate a download of 115.0.1 if 115 was already installed, but not if 102 was the existing version. And if you already had the outlook accounts set up, there would have been no need to log in again.

Without knowing these details, I can't say why the warning appeared.

TB was automatically updated until 115.0.1 which required download and install. I don't know the version was but was the latest version before 115.0.1. Accounts had set up without any problem. The Security Risk warning to outlook account is strange. I thought someting might happen between Mozilla and Microsoft so that outlook is put in blacklist. Seems this is not the case as it works with you. I may revert back to earlier TB vesion and see. Thanks for the replies.

If TB updated from 102* to 115 then it was not Thunderbird who controlled the update. You were informed of an update discovered by a program on your computer which auto checks for updates for apps on your computer.

If you were using 115 and got updated to 115.0.1 then it might be Thunderbird, but I'm more inclined to think it was whatever program you have got installed to check for updates for apps installed on computer.

If Thunderbird was controlling the update then you would still be using 102.13.1

re :No antivirus was installed. If using Windows OS then it has a default Anti-Virus product built in.

Thanks all for replies. I have reinstalled an old version 102.0.1, all the issures are gone. I will stay in the old version till next release.