404 FILE NOT FOUND, MICROSOFT TEAMS

The 404 error when opening the OneDrive app inside Microsoft Teams can occur after a change to the account’s User Principal Name (UPN). In this case, the OneDrive URL that Teams is trying to open no longer matches the updated UPN.

Use this workaround to re-establish access from Teams:

1. In Teams, start a one‑on‑one chat with another user.
2. In the message compose box, select Actions and apps > Attach file > Upload from this device.
3. Choose any local file and select Open.
4. Send the message so the file uploads.
5. After the file is sent, select the OneDrive app from the left navigation bar again.

This sequence forces Teams to reconnect to the correct OneDrive location for the account. If the UPN was recently changed, also review how UPN changes affect OneDrive URLs and features as described in the linked documentation.

If the error persists and the content truly cannot be found, the OneDrive or SharePoint resource may have been moved, renamed, or deleted. In that case, contact the Microsoft 365/SharePoint administrator to verify the site or file status and restore it if necessary.

References:

• "404 File not found" error when accessing the OneDrive app in Teams
• "Error: 404 File/Page not found" in OneDrive or SharePoint