When a guest accepts a SharePoint Online invitation by using another account Then grant the user permissions back to the file or site. Make sure that the user is removed from the site collection. If there are still errors with the account, we recommend that you completely remove the guest account from the Microsoft 365 admin center. If the user doesn't have appropriate permissions, grant them permissions to the file or site. Verify the permissions by using the Check Permissions feature: If the user is trying to access another user's OneDrive site After the ticket is opened, provide the support agent with the UPN and OneDrive URL that's having the issue.At the bottom of the pane, select Contact Support > New Service Request.As an administrator, select OneDrive Site User ID Mismatch, it will populate a help query in the admin center.If you can't restore the original user and are still in this state, create a support request: To fix this issue, delete the new UPN if it exists, and then restore the original UPN. If users have already signed into SharePoint, are moved to a different OU that's not currently synchronized with Microsoft 365, and then resynced with SharePoint, they may experience this problem. A second scenario involves directory synchronization with an Active Directory organizational unit (OU). When the user tries to access a site collection or OneDrive, the user has an incorrect ID. The new account is created by using a different Unique ID value. This issue most frequently occurs when a user is deleted and re-created with the same user principal name (UPN). When accessing a OneDrive site If the user is the owner of the OneDrive site If the user continues to receive an error message, remove the user from the site.

If the user doesn't have appropriate permissions, grant the user permissions to the file or site. Review the permissions the user has on the site, and through which security group (if applicable).In the User/Group field, enter the user's name, and then select Check Now.In the top ribbon, select Check Permissions.Verify the permission by using the Check Permissions feature: When accessing a SharePoint siteДetermine the permission level that the user should have on the site (member, owner, and so on). In your scenario, replace with the domain that's used for your organization. Many examples in this article use as a placeholder.

Chronosync permission denied