MS Teams: The request is not properly formatted. The parameter 'login_hint' is duplicated
This happened to me today. After my corporate IT team made some changes to my account, I found that when I tried to switch from MyCompany's Teams org to aClient's Teams org (same email/account, I'm a "guest" in the second org) I got the 'login_hint' message above.
I tried the above solution about deleting the contents of %appdata%\Microsoft\Teams but it didn't help.
The solution I found was (simply, and slightly depressingly) to Sign Out of Teams and sign back in again. This seemed to trigger something that fixed the problem.
Hope this helps someone...
This worked for me. Enabled the "Advanced diagnostics" and quit the Teams. Weird but worked!
Hope it helps you too.
What helped for me was erasing cache as written in Microsoft forums.
https://answers.microsoft.com/en-us/education_ms/forum/all/ms-team-issue-similar-to-incident-tm173756/c1dbb4e0-74e8-4d0b-8042-797bbe5142a7
Marvin Ma MSFTReplied on April 29, 2019 Microsoft Agent | Moderator Hi Chabbi,
I've checked the incident TM173756 and it was resolved in February 18, 2019. So your issue could be caused by different factors. Based on the error, you cannot sign in Teams. In this scenario, please follow the steps below to check if it helps.
Fully exit the Microsoft Teams desktop client. To do this, either right click Teams from the Icon Tray and select ‘Quit’, or run Task Manager and fully kill the process.
Go to File Explorer, and type in "%appdata%\Microsoft\teams".
Once in the directory, delete all the files and re-open Teams.
Meanwhile, please check if you can sign in Teams on the web. It will help us determine whether it's a client issue. For the further investigation, please capture a screenshot of the entire error message and upload in the post.