Why am I receiving a 401 'Unauthenticated' error when downloading files from OneDrive?

Below is an analysis of your issue based on the information provided:

Problem Summary

You can perform read and search operations on OneDrive files and folders, but when you try the download file operation, you receive an error:

401 - "{\"error\":{\"code\":\"unauthenticated\",\"message\":\"Unauthenticated\"}}"

Despite recreating the Microsoft OneDrive OAuth2 credentials and testing on another computer, the connection and other operations (like search and get) work fine—only downloading files fails.

What This Error Means

A 401 "Unauthenticated" error coming directly from the Microsoft OneDrive API indicates that the request for downloading the file is not authorized. This usually boils down to one of the following:

• Token Scope or Permission Issue: Although your credentials work for reading and searching, the download operation might require additional permissions or a different scope that isn’t properly granted.
• Access Token Issue: There might be a problem with the token refresh process or the token being used for this particular operation is not valid for file download.

Troubleshooting Steps

1. Review OAuth2 Scopes:
   Verify that the OAuth2 app registration in Microsoft includes all the necessary permissions for file download. Even though reading files works, ensure that permissions like Files.Read, Files.Read.All (or equivalent) are also enabled. It’s not uncommon for some operations to require specific or more granular scopes.

2. Validate the API Settings:
   Double-check the endpoint or settings for the download operation in your node configuration. Even if the credentials are correct, an incorrect setting could lead to an endpoint expecting different authentication details.

3. Re-Authorize Credentials:
   Although you mentioned you deleted and recreated the credentials, try re-authenticating while explicitly validating that all requested scopes are correctly authorized during the OAuth flow.

4. Compare Other Operations:
   Since other nodes (read and search) are working, compare their settings against the download operation. See if any additional configuration is required specifically for the download operation.

5. Check Microsoft’s Documentation:
   Refer to Microsoft’s OneDrive API documentation for file download operations to ensure there are no recent changes or additional parameters required that could affect authorization.

Conclusion

The error indicates that while your connection is overall working, the token used for downloading files isn’t carrying the necessary authentication or permissions. Double-checking OAuth scopes, ensuring correct operation settings, and reviewing API endpoint requirements should help resolve this issue.

If the problem persists after these checks, consider contacting support or checking community forums for any recent changes to OneDrive's API behavior regarding downloads.

Feel free to ask if you have more questions about using Microsoft OneDrive with n8n!