Error loading add-in ... while manifest is ok

Copper Contributor

I developped an Excel web addin with an aspnet core 6.0 API and published it on a dedicated server on Azure.
Excel raise an "Error loading add-in" error when the complement is installed on Excel.
Please note that :
- the xml manifest has been validated (common error in this case)
- cors is enabled
- the api has been tested online with swagger

Does any one have a suggestion ?


1 Reply


Here are some simple troubleshooting steps for the "Error loading add-in" issue:

  1. Check Manifest URL: Make sure the URL in your manifest file is correct and can be accessed from Excel.

  2. Network Settings: Ensure your server allows traffic from Excel and that there are no firewall issues.

  3. SSL/TLS: If you're using HTTPS, make sure it's set up correctly with a valid certificate.

  4. Server Logs: Look for any errors or warnings on your server that might explain the issue.

  5. Excel Logging: Enable logging in Excel to get more details about the problem.

  6. Excel Version: Make sure your Excel version is compatible with your add-in.

  7. Test on Another Machine: Try your add-in on a different computer to see if the problem persists.

  8. Revalidate Manifest: Double-check your manifest file for any mistakes.