Outlook keeps asking for a password and will not accept it

Always start here. Clearing one store and not the others is why this fault appears to come back.

1. Close Outlook and Teams completely — check Task Manager, because both leave background processes that hold the tokens.

   PowerShellCopy

   Get-Process OUTLOOK,ms-teams,Teams -ErrorAction SilentlyContinue | Stop-Process -Force

2. List the Office-related credentials before removing them.

   PowerShellCopy

   cmdkey /list | Select-String -Pattern 'MicrosoftOffice|MS.Outlook|SSO_POP|OneDrive'

3. Remove the Office entries.

   PowerShellCopy

   cmdkey /list | ForEach-Object {  if ($_ -match 'Target:\s*(MicrosoftOffice\S+|MS\.Outlook\S+|SSO_POP\S+)') { cmdkey /delete:$($Matches[1]) }}

   These are the entries Outlook consults before it prompts. Leaving one behind means the prompt you fill in is discarded in favour of the stale entry, which is precisely the loop being reported.

4. Open Outlook. It should prompt once and then stay signed in.

5. If the prompt returns, sign out of Office entirely from File → Office Account → Sign out, restart, and sign back in.

cmdkey /list | Select-String -Pattern 'MicrosoftOffice'

Clearing credentials did not hold, or the machine has been rebuilt or moved between tenants.

1. Close all Office applications.

2. Back up the identity keys before removing them.

   PowerShellCopy

   reg export "HKCU\Software\Microsoft\Office\16.0\Common\Identity" "$env:USERPROFILE\Desktop\identity-backup.reg" /y

3. Remove the cached identities.

   PowerShellCopy

   Remove-Item 'HKCU:\Software\Microsoft\Office\16.0\Common\Identity' -Recurse -Force

   This is where Office records which account is signed in and which tenant it belongs to. After a tenant migration or a rebuild it can hold an identity that no longer exists, and no prompt will ever satisfy it.

4. Clear the Web Account Manager cache, which holds the token itself.

   PowerShellCopy

   Get-ChildItem "$env:LOCALAPPDATA\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\AC\TokenBroker\Accounts" -ErrorAction SilentlyContinue | Remove-Item -Force -Recurse

5. Restart and sign in to Outlook fresh.

Neither of the above worked. A damaged profile cannot be repaired reliably and rebuilding is faster than trying.

1. Note the account details and any PST files in use before starting.

   Command PromptCopy

   control mlcfg32.cpl

2. Create a new profile rather than modifying the existing one, and set Outlook to prompt for a profile so you can switch back.

3. Add the account and let autodiscover configure it. Do not use manual settings for a Microsoft 365 mailbox — the manual path skips modern authentication and reintroduces the prompt loop.

4. Re-attach any PST files by File → Open & Export → Open Outlook Data File.

   Local PST archives are not re-added by a new profile, and their absence is the thing most likely to be reported as data loss after this fix. Re-attaching is two clicks if you noted the paths first.

5. Once the new profile is proven, set it as default and remove the old one.