Outlook Classic Keeps Asking for Password (Microsoft 365): Fix Modern Auth, WAM Token Cache, and Credential Loops (2026)
Outlook Classic repeatedly asking for your Microsoft 365 password is almost never about the password itself. It is usually a Modern Authentication token issue caused by stale Windows credentials, a broken WAM broker (Microsoft Entra BrokerPlugin), or Outlook falling back to legacy prompts. This guide fixes the loop with a safe escalation path, from Credential Manager cleanup to broker repair and profile rebuild.
The Problem
When Outlook Classic enters a password loop, users typically report one of these patterns: Outlook launches and immediately shows a credential prompt, the password is accepted but the prompt returns, or the status bar flips between "Need Password" and "Trying to connect." In some environments it happens after MFA completes, after a Windows update, or only when switching networks or waking from sleep.
This is disruptive because Outlook does not "partially fail." Even a single broken authentication path can block mail sync, calendar updates, and access to shared mailboxes. The good news is that the root cause is usually local to the workstation: cached credentials, token broker state, or profile bindings that drifted over time.
Step-by-Step Guide
Confirm it's a client-side Outlook Classic issue
Avoid fixing the workstation when the problem is tenant-side or account-side.
Start by checking whether the identity itself is healthy. Sign in to Outlook on the web in a browser using the same account. If web access works, the mailbox and credentials are fine and the loop is almost certainly local to Windows or Outlook Classic.
If web access fails too, check for account lock, recent password resets, Conditional Access changes, or MFA registration issues before touching the workstation.
Remove "forced credential prompts" settings in Outlook
Ensure Outlook is not configured to always request credentials.
In Outlook Classic, open File → Account Settings → Account Settings, select the Microsoft 365 account, then check advanced and security options. In some configurations, a non-default security setting can contribute to repeated prompts, and Microsoft documents credential loops tied to these settings.
After adjusting, fully close Outlook (including from the notification area) and reopen it once.
Clear Outlook and Office entries from Windows Credential Manager
Remove stale credentials that Outlook keeps reusing.
Close Outlook and Teams. Then open Control Panel → Credential Manager → Windows Credentials. Remove entries clearly related to Office and Outlook, especially those mentioning Outlook, MicrosoftOffice, ADAL/MSAL, or Exchange-related targets. Microsoft's guidance specifically points to stored credentials as a common cause of repeated prompting.
Restart Windows after cleaning. A reboot matters because brokered tokens and sign-in processes can remain cached until the session resets.
cmdkey /list
REM Delete a specific credential target (replace with the exact target name)
REM cmdkey /delete:<TARGET_NAME>Sign out of Office across apps, then sign back in
Rebuild the Office identity state cleanly.
Open an Office app like Word, go to File → Account, and sign out of all accounts shown. Then close all Office apps including Outlook and Teams. Reboot, and sign back in using the correct work account.
This step looks basic, but it forces Office to rebuild the sign-in context instead of carrying forward a broken identity chain from previous sessions.
Repair the WAM token broker (Microsoft Entra BrokerPlugin)
Fix "Need Password" states caused by broken WAM components.
If Outlook still flips to "Need Password" without user interaction, or prompts continue after Credential Manager cleanup, the Windows broker may be the real problem. Microsoft documents a supported remediation: reinstall the Microsoft Entra WAM plugin package for work accounts using PowerShell.
Run the command below in an elevated terminal, then reboot and test Outlook again.
# Re-register BrokerPlugin if missing/corrupted (Microsoft-supported approach)
Add-AppxPackage -Register "$env:windir\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Appxmanifest.xml" `
-DisableDevelopmentMode -ForceApplicationShutdownForce OAuth for Autodiscover (only if your scenario matches)
Stop Outlook from falling back into legacy prompting behavior for certain flows.
In specific scenarios, Outlook can prompt for a password even when Modern Authentication is enabled. Microsoft documents a supported registry value that forces Outlook to use OAuth for Autodiscover.
Apply this under the affected user context, then restart Outlook. If the environment does not match the documented scenario, do not apply this "just in case."
reg add "HKCU\Software\Microsoft\Exchange" /v AlwaysUseMSOAuthForAutoDiscover /t REG_DWORD /d 1 /fCreate a new Outlook profile (high success rate)
Remove corrupted auth bindings and rebuild account configuration.
If the loop persists, treat the Outlook profile as suspect. Open Control Panel → Mail → Show Profiles, add a new profile, and set it as default for testing. Add the Microsoft 365 account and complete MFA once.
A new profile often resolves cases where the account is healthy but the profile's cached auth state is inconsistent or stuck.
Test Safe Mode and disable problematic add-ins
Rule out add-ins intercepting sign-in flows or breaking embedded auth UI.
Launch Outlook Safe Mode and observe whether the password loop disappears. If it does, an add-in is very likely interfering. Disable non-essential COM add-ins, restart Outlook normally, and re-enable add-ins one by one to identify the trigger.
This is especially common with older CRM connectors, archive add-ins, or security plug-ins that hook authentication windows.
outlook.exe /safeRepair Microsoft 365 Apps (Office)
Fix broken client components and sign-in UI behavior.
Go to Settings → Apps → Installed apps → Microsoft 365 → Modify and run Quick Repair first. If the issue persists, run Online Repair. Microsoft documents sign-in failures that can be influenced by security software or corrupted components, and repair is a supported stabilization step.
After repair, reboot and test Outlook again.
Do not "fix" this by disabling ADAL or WAM
Prevent unsupported changes that create bigger problems later.
If you find guides advising you to disable ADAL or WAM via registry, treat that as a red flag. Microsoft explicitly states this approach is not supported and can adversely affect your environment.
If you are still stuck after the supported steps above, escalate with logs (Office sign-in logs, Entra sign-in logs, Outlook connection status) rather than forcing legacy auth behavior.
How It Works
Modern Microsoft 365 authentication for Outlook is token-based. Outlook requests OAuth tokens to access Exchange Online. On Windows, those tokens are typically brokered and stored through the Web Account Manager (WAM) stack, which depends on system components like the Microsoft Entra BrokerPlugin package for work accounts. If WAM cannot issue tokens, or if stale credentials are repeatedly supplied from Windows Credential Manager, Outlook may fall back into a classic prompt loop even though the account is healthy.
Two common failure modes create the "keeps asking for password" symptom:
First, Outlook is actually receiving an authentication challenge that it cannot satisfy with the cached token it has, so it prompts again and again. This is often caused by broken token cache entries, broker package issues, or security software interfering with the sign-in dialog.
Second, Outlook is not using the expected Modern Auth flow for certain discovery or connection scenarios, which makes it behave as if Basic-style prompting is required. In those cases, Microsoft documents a supported registry value to force OAuth for Autodiscover when the scenario matches.
One important rule for enterprise admins: disabling ADAL or WAM to "make prompts go away" is not a supported fix and can put the Office client into an undesirable legacy state. Use supported remediation steps instead.
Frequently Asked Questions
Because the loop is usually caused by token acquisition or token storage failures, not an incorrect password. Stale credentials in Windows Credential Manager or a broken WAM broker commonly triggers repeated prompts.
WAM is the Windows token broker used by Microsoft 365 apps to obtain and store OAuth tokens. If the BrokerPlugin or related components fail, Outlook can't refresh tokens reliably and falls into "Need Password" loops.
Yes, it is one of the most effective first fixes. It removes stale saved credentials that Outlook may keep reusing. You will need to sign back into Office apps afterward.
Only when your scenario matches Microsoft's documented behavior where Outlook prompts despite Modern Auth being enabled. Use it as a targeted fix, not a generic tweak.
Not when the loop persists after credential and broker repairs. A new profile rebuilds account bindings and often resolves stubborn cases with minimal risk to server-side data.
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