Error in Outlook Classic with credential invalid

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Error in Outlook Classic with credential invalid

danl 0

Outlook classic began throwing off errors today and I keep getting this when I try to fix the account

Correlation Id: [Moderator note: personal info removed]

Timestamp: 2026-05-06T00:24:57.000Z

DPTI: [Moderator note: personal info removed]

Message: The credential is invalid. Unexpected sub status (6008).

Tag: 657rx

Code: [Moderator note: personal info removed]

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danl 0

Thank you I did but it was unsuccessful. I had to engage a 3rd party to investigate, it seems the office 365 even after a reinstall would not remove old tokens and was not allowing the appropriate logins to occur. Major registry edits to work it out and clean it up and even after that it only resolved getting the subscription authorized 1 exchange account was still corrupt and was only resolved by switching the the new outlook

Hani-Ng 11,315 Reputation points Microsoft External Staff Moderator

2026-05-08T03:27:20.1266667+00:00

Hi danl

Thank you for sharing your experience. It sounds like the old authentication tokens in the registry may have become invalid. This can sometimes cause issues with sign-in or syncing, which can sometimes persist even after a standard reinstall. 'New Outlook' seems to handle authentication a bit differently, which might explain why it was able to bypass the old tokens and allow the Exchange account to connect.

I appreciate you updating the thread, as this could be very helpful for other community members running into similar situations.

Thanks again for contributing to the community!

Best regards.

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Hani-Ng 11,315 Reputation points Microsoft External Staff Moderator

2026-05-08T03:27:20.1266667+00:00

Hi danl

Thank you for sharing your experience. It sounds like the old authentication tokens in the registry may have become invalid. This can sometimes cause issues with sign-in or syncing, which can sometimes persist even after a standard reinstall. 'New Outlook' seems to handle authentication a bit differently, which might explain why it was able to bypass the old tokens and allow the Exchange account to connect.

I appreciate you updating the thread, as this could be very helpful for other community members running into similar situations.

Thanks again for contributing to the community!

Best regards.

Answer 1

Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

Hi danl

Based on the error code you shared, I found several troubleshooting steps you can try:

Sign out your accounts from Office applications, then close all Office applications.
Open File Explorer, paste the following path, and delete all files and folders you find inside this location: %localappdata%\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy
In the Windows search bar, search for "Access Work or School" > check if you can see your business account in "Access Work or School".
- If you don't see it, please select Connect and add your business account.
- If you can see it, please select it and select Disconnect. After that, please click Connect and log into your account again.
Finally, run one Office application, sign into your account, and check again.

I hope this helps and if you have any question, please feel free to ask via comment section.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Hani-Ng 11,315 Reputation points Microsoft External Staff Moderator

2026-05-07T06:07:29.9666667+00:00

Hi danl

Just checking in to see if you've had a chance to check my previous reply.

Please let me know if you have any further questions.

Answer 2

The error indicates an authentication/credential problem in classic Outlook. Based on similar Outlook credential issues, use these steps to troubleshoot:

Remove cached Windows credentials
- Open Control Panel → User Accounts → Credential Manager → Windows Credentials.
- Remove any entries related to Outlook, Office, Microsoft 365, or the affected email account.
- Close Credential Manager.
- Restart Outlook and sign in again when prompted.
Verify the password and any required app password
- If the mailbox uses an external provider (for example, Gmail, Yahoo, or another service that requires app passwords), confirm that the correct app password is used, not a different provider’s app password. A known issue is using a Microsoft app password instead of the provider’s app password in Outlook Classic.
- If the account password was recently changed on the provider’s website, update it in Outlook when prompted.
Confirm account type and configuration
- For Microsoft consumer accounts (for example, Hotmail.com or Live.com), ensure the account is added in classic Outlook using the correct account type (for example, Outlook.com, not Exchange or Microsoft 365). Incorrect account type can cause repeated credential failures.
Create a new Outlook profile (if prompts persist)
- Open Control Panel → Mail → Show Profiles.
- Create a new profile and add the account again.
- Set the new profile as default and test whether the credential error still occurs.
Check for broader sign-in or service issues
- If multiple users in the organization are affected at the same time, check the Microsoft 365 Service Health Dashboard for any current incidents related to Outlook sign-in.

If the problem continues after clearing credentials, confirming the correct password/app password, and recreating the profile, involve the organization’s IT/admin team to review authentication policies, certificates, or conditional access that might be rejecting the token and causing the “credential is invalid” error.

References:

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Error in Outlook Classic with credential invalid

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