How to fix "Can't Authenticate you" in MS Teams while outlook stops syncing at the same time?

Question

Hello,

Single user in our organization (of 100+ business licensed members) has this error in MS Teams for about 4-5 months now, error happens randomly. Lately, it is happening every 24-36 hours. After PC restart it disappears.

Previously, after getting this warning, the user wouldn't be able to see incoming teams calls, messages. Most of the times, when this warning happened in MS Teams client, MS outlook desktop app would also bug out and not update anything - newest emails wouldn't appear in outbox and etc.

User has Microsoft Business Standard account.

Users PC: Windows 11, all the windows updates are installed until today. (2025-02-03).

I tried troubleshooting the problem via microsoft help forums, chatgpt and microsoft support ticket. Tried other methods, but nothing seemed to fix the problem. I have reset windows with files deletion and other data deletion. Previously, before pc reset, user had his personal email signed in somewhere and I thought that the authentification error happened because windows was trying to authenticate users personal MS Teams account while the user was using his work teams account.

Regarding the PC: After full pc reset, which I did one week ago, I've downloaded the latest 365 pack, signed in to all apps with the users MS work account. Installed all the newest windows updates + DELL pc updates. The user is logged in to windows 11 via local admin account, no other accounts are created. Under accounts, the user isn't connected to personal/other microsoft accounts, only connected via work account with microsoft credentials. User hasn't got personal teams account connected like previously.

Regarding the users 365 MS Account: I have checked MS365 account if there were any devices that were memorized to that account, but there was only one, the current PC. I've also reset the users password in 365 admin, disabled 2FA auth in Entra + in MFA Settings I Deleted all existing app passwords generated by the selected users + Restored multifactor authentication on all remembered devices. I tried before several times deleting teams cache, reseting the app, reinstalling it and etc.

Regarding NETWORK+Firewall - I've checked and I didn't find anything blocking MS Teams or outlook ports. User works alongside 30 other users on the same LAN with the same network/firewall settings, and only this particular user gets the bugs in teams and bugs outlook.

C:\Windows\System32>dsregcmd /status   +----------------------------------------------------------------------+ | Device State                                                         | +----------------------------------------------------------------------+                AzureAdJoined : NO           EnterpriseJoined : NO               DomainJoined : NO            Virtual Desktop : NOT SET                Device Name : USER-DELL   +----------------------------------------------------------------------+ | User State                                                           | +----------------------------------------------------------------------+                       NgcSet : NO            WorkplaceJoined : YES           WorkAccountCount : 1              WamDefaultSet : NO   +----------------------------------------------------------------------+ | SSO State                                                            | +----------------------------------------------------------------------+                   AzureAdPrt : NO        AzureAdPrtAuthority : NO              EnterprisePrt : NO     EnterprisePrtAuthority : NO   +----------------------------------------------------------------------+ | Work Account 1                                                       | +----------------------------------------------------------------------+            WorkplaceDeviceId : XX        WorkplaceThumbprint : XX DeviceCertificateValidity : [ 2025-01-23 13:32:55.000 UTC -- 2035-01-23 14:02:55.000 UTC ]             KeyContainerId : XX                KeyProvider : Microsoft Platform Crypto Provider               TpmProtected : YES          WorkplaceTenantId : XX       WorkplaceTenantName : OURORGANIZATIONNAME            WorkplaceMdmUrl :       WorkplaceSettingsUrl :                     NgcSet : NO   +----------------------------------------------------------------------+ | IE Proxy Config for Current User                                     | +----------------------------------------------------------------------+         Auto Detect Settings : YES     Auto-Configuration URL :          Proxy Server List :          Proxy Bypass List :   +----------------------------------------------------------------------+ | WinHttp Default Proxy Config                                         | +----------------------------------------------------------------------+                  Access Type : DIRECT   +----------------------------------------------------------------------+ | Ngc Prerequisite Check                                               | +----------------------------------------------------------------------+               IsDeviceJoined : NO              IsUserAzureAD : NO              PolicyEnabled : NO           PostLogonEnabled : YES             DeviceEligible : YES         SessionIsNotRemote : YES             CertEnrollment : none               PreReqResult : WillNotProvision   For more information, please visit https://www.microsoft.com/aadjerrors

This is the output of dsregcmd. I've changed workplace and other sensitive data with XX. Maybe something isn't connected all the way through?

Credentials: Web credentials are empty, Windows credentials are generic credentials (virtualapp/didlogical and SSO_POP_Device). No office/outlook/microsoft credentials in PC.

Using Teams web via chrome or edge works fine for the user. Haven't tested if the same issue is appearing on web though since they've been on the web version only for short period.

All available updates are installed that I could think of. Troubleshooting Teams Sign In problems in 365 admin console or SARA troubleshooters don't give any dividends. Classic.

Has anyone faced this issue? I thought that it was microsoft exchange crashing/bugging out, but there was a few separate days that the user got this warning and outlook didn't glitch and he could use teams as usual - make calls, write messages and etc. Also quick note - after the windows reinstall, user had 3 or 4 times this error and also two of the times outlook glitched out as well.