How to fix "native_auth_error: See https://aka.ms/msal.js.errors#native_auth_error for details"

Hi Nicole,

Thank you for the detailed update.

Since the Claude add-in works in Outlook on the web but not in the Windows app, this does point to a client-side issue with the new Outlook for Windows, rather than your account or permissions.

Given that the Repair option didn’t run, here are the next steps I recommend:

1/ Clear the add-in’s local/session storage (authentication cache)

For add-in authentication errors like native_auth_error, clearing the local web storage often helps resolve sign-in issues:

• Close the new Outlook app
• Press Windows + R, then run: olk.exe --devtools (Make sure there is a space before “--”)

Then:

Open the Claude add-in

Right-click inside the add-in pane > select Inspect

Go to the Application tab

Under Storage, clear:

• Local Storage
• Session Storage

If a separate sign-in/auth window appears, repeat the same steps there

Close Outlook and reopen it, then test again.

2/ Reinstall the new Outlook for Windows (client refresh)

Since the add-in has already been reinstalled, the next step is to refresh the Outlook client itself:

• Fully close new Outlook for Windows
• Uninstall it from the Start menu
• Reinstall it from the Microsoft Store

You can refer to this guidance: Outlook for Windows not responding, hangs, freezes, or stops working

If the issue still persists after reinstalling new Outlook, I would recommend the following escalation options:

• Contact the add-in provider (Claude for Outlook): According to Microsoft’s guidance on Office add-ins, if the issue continues, the best next step is to reach out to the add-in developer directly using the Details + support section on the add-in’s page.

For reference: Office Add-ins known issues - Office Add-ins | Microsoft Learn

• Open a Microsoft 365 support request: Since you’re both the business owner and a Global Administrator, you can also submit a support ticket directly through the Microsoft 365 admin center by following this guide: Get support - Microsoft 365 admin | Microsoft Learn .

I hope this helps point you in the right direction. If you have any questions or need further clarification, please feel free to let me know. I’m happy to assist.

If you found my answer helpful, I would truly appreciate it if you could mark it as the “Accepted Answer.” Doing so will pin it to the top of the thread, making it easier for others in the community to find the right guidance quickly. Your contribution not only confirms the solution but also helps fellow users who may face the same challenge. 

Thank you once again, and I wish you a wonderful day.

Hi @Nicole Vorkapic

Good day, and I appreciate the clear explanation of your concern.  

Based on the issue you described, you can try the following troubleshooting steps:

1/ Test the add-in in Outlook on the web

The add-in is supported in Outlook on the web as well as the new Outlook for Windows. If it works correctly in Outlook on the web but not in the Windows app, this likely indicates a client-side issue rather than a problem with your account.

2/ Remove and re-add the add-in

As this is a beta add-in, refreshing its configuration may help:

• Remove the add-in from Outlook
• Reinstall it to clear any stale or corrupted local data

3/ Ensure WebView2 is installed and functioning properly

Office add-ins rely on Microsoft Edge WebView2 to run correctly. If the WebView2 runtime is missing or not functioning properly, Outlook add-ins may fail to load or operate as expected. In most cases, Microsoft 365 installs this component automatically on supported systems.

To verify its presence:

• Go to Control Panel > Programs > Programs and Features
• Look for Microsoft Edge WebView2 Runtime in the list.
• If you see Modify or Advanced options, use Repair if available.
• After repairing:
  • Restart Windows
  • Open Outlook
  • Test the Claude add-in again.

For reference: Microsoft Edge WebView2 and Microsoft 365 Apps

4/ Repair the Outlook app 

• Open Window Settings
• Go to Apps > Installed Apps
• Find Outlook, click the three dots, and then select Advanced options
• Click Repair and test the problem
• If the problem persists, go back to the same menu and click Reset.

5/ Contact your IT admin 

If the issue continues, please reach out to your IT administrator for further assistance. They can investigate further or submit a support request through the Microsoft 365 Admin Center by following the steps here: Get support - Microsoft 365 admin | Microsoft Learn . 

If you’re unsure who your IT admin is, you can find guidance here: How do I find my Microsoft 365 admin? - Microsoft Support. 

Note: We appreciate your understanding regarding the scope of support available through this forum. As moderators, our role is to provide general guidance and assist with common troubleshooting steps. While we do not have access to internal systems or administrative tools required to resolve account-specific or backend-related issues but we’ll continue doing our best to support you within the scope of our responsibilities. 

I hope this helps you move forward. If you have any questions or need further clarification, please feel free to reach out. I’ll be happy to assist further. 

Thank you for your patience and understanding, and I look forward to supporting you. 

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