Fix ID mismatch in SharePoint or OneDrive is a common issue that occurs when a user returns to your organization or a new account is created using the same email or initials as someone previously deleted. Although permissions may appear correct, the user can suddenly be blocked from accessing shared files or sites with an “Access Denied” error. This happens because SharePoint continues to reference the internal ID of the deleted account, creating a hidden conflict that breaks access.
If you need to fix ID mismatch in SharePoint or OneDrive, Microsoft provides a simple diagnostic tool that helps resolve the problem quickly and without the need for PowerShell or manual cleanup.
What’s Happening?
Behind the scenes, SharePoint stores internal user IDs. If a user is deleted and later re-created with the same UPN (email address) or initials (e.g. abc@domain.com), SharePoint may still hold onto the old ID from before. This mismatch breaks permissions, even if they look fine in the UI.
The Easy Fix
Microsoft has created a built-in diagnostic tool to fix this exact issue. Here’s how to use it:
- Go to: aka.ms/PillarSiteUserIDMismatch
- Sign in as a Global or SharePoint Admin.
- Enter the affected user’s UPN (email address) and the URL of the site where access is failing.
- Re-share the specific files or folders.
This usually solves the problem right away. In some cases, it can take up to 24 hours for everything to fully sync.
Summary
This issue typically occurs when a user is re-created after being deleted or when a new account is made using the same initials or email address as a former user. In these cases, SharePoint may still associate permissions with the old internal identity, causing unexpected access problems. Running the Microsoft diagnostic tool helps remove the outdated reference and quickly restores the correct access.
Keep this one bookmarked. It is a simple fix for a problem that can be surprisingly difficult to troubleshoot.