A Microsoft file hosting and synchronization service.
A 403 Forbidden error when accessing OneDrive after moving to Microsoft Entra ID usually indicates that the account can authenticate but does not currently have permission to access its OneDrive site.
To help narrow this down, could you check the following?
- Confirm that the affected user has an active license that includes OneDrive for Business (SharePoint Online).
- Try opening OneDrive from the Microsoft 365 app launcher or by browsing to: https://<yourtenant>-my.sharepoint.com
- Verify whether the user’s OneDrive has been provisioned successfully. If the personal site has not yet been created, a 403 error can occur.
- Sign out of all Microsoft 365 accounts in the browser, then test again in an InPrivate/ Incognito window using only the affected work account.
You may also find these Microsoft articles helpful:
- Error 403 Forbidden in OneDrive or SharePoint - SharePoint | Microsoft Learn
- Access Denied or You need permission errors in SharePoint Online and OneDrive - SharePoint | Microsoft Learn
Could you also clarify:
- Does this affect only one user or multiple users?
- Does the error occur in both the browser and the OneDrive sync client?
- What is the full URL the user is trying to access?
- Was the user’s UPN or sign-in address changed during the migration?
- Has the user’s OneDrive site been confirmed to exist in the SharePoint admin center?
If everything above has already been verified and the issue began after the migration to Microsoft Entra ID, it may require your Microsoft 365 administrator to review the tenant configuration or open a support request with Microsoft, as those checks are beyond what can be performed through the Community forum.