Office TPM ERROR 2146893802

Dear @PO Boligudlejning,

Good day, and I appreciate the detailed description of your issue. From my research, this error typically occurs because Outlook (and other Microsoft 365 applications) store authentication tokens and credentials encrypted using the device’s Trusted Platform Module (TPM). When a PowerShell script is executed using Basic Authentication against Office 365 SMTP, it can lead to conflicts or corruption within the cached modern authentication tokens. This scenario is especially common on Windows virtual machines, particularly after running scripts that rely on legacy authentication methods, which Microsoft has been actively deprecating.

The sub‑status code 6008 specifically indicates invalid or corrupted cached credentials that are tied to the TPM. To address this, please follow the steps below to see if they resolve the issue.

1.Clear the AAD Broker Plugin Cache 

1. Close Outlook completely (check Task Manager > End any Outlook or Office processes).
2. Press Windows + R, type the following and press Enter: %localappdata%\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy
3. Delete all contents of this folder (or the entire folder if possible).
4. Restart your VM.

2.Clear Windows Credentials

Search for Credential Manager in the Start menu and open it.

Go to Windows Credentials.

Remove any entries that contain:

• MicrosoftOffice
• Office16
• Outlook
• Your Office 365 / SMTP email address
• AzureAD or AAD

Also check Generic Credentials and remove similar entries.

3.Disconnect and Reconnect the Work/School Account

• Go to Settings > Accounts > Access work or school.
• Find your Microsoft 365 / company account > click it > select Disconnect / Remove.
• Restart the VM.
• Go back to Access work or school > click Connect and re-add your Microsoft 365 account.

4.Sign Back into Outlook

• Open Outlook.
• It should prompt you to sign in again with modern authentication (not Basic Auth).
• Complete the sign-in (you may need to approve MFA if enabled).

5.(Optional but Recommended) Repair Office

• Go to Settings > Apps > Installed apps.
• Find Microsoft 365 or Microsoft Office > Modify > choose Online Repair.

Additional notes for Windows VMs

• Avoid using Basic Authentication in PowerShell scripts for SMTP going forward (Microsoft has fully deprecated it for most tenants). Use Modern Authentication with the Microsoft Graph or Exchange Online PowerShell module instead.
• If this VM is frequently cloned or snapshotted, TPM-related issues can reappear. Consider using a persistent credential approach or disabling TPM dependency if possible in a non-production VM.

I hope this information is helpful. Please follow these steps and let me know if it works for you. If not, we can work together to resolve this. Thank you for your patience and understanding. If you have any questions or need further assistance, please feel free to share them in the comments so I can continue to support you. I'm looking forward to your reply.

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