Fix "Data Validation Failure Error" in Azure AD

Hi @Hugh O'Keeffe , can you manually update the UPN attribute on AAD? If that still doesn't work follow these troubleshooting steps:

1. Verify that the UserPrincipalName (UPN) attribute you fixed on-premises meets the validation requirements of Azure AD.
2. Ensure that the on-premises user object has been synchronized to Azure AD after the UPN attribute change. You can force a synchronization using Azure AD Connect.
3. Check the Synchronization Service Manager to see if there are any descriptive errors on the object.
4. If the issue persists, consider reviewing other attributes that might be causing the validation failure, such as the MailNickName attribute.

Please let me know if you have any questions and I can help you further.

If this answer helps you please mark "Accept Answer" so other users can reference it.

Thank you,

James

I found this post because of the same error message. I found that it was because we used o with an accent mark and then found this article saying that the allowed characters in a username are A-Z, a-z, 0-9.\

"Invalid user name" when you try to create a user name that contains a special character in Microsoft 365\

You can use a wider range of characters in the Display Name, so this met the requirements. The Display name can include ó and á but the username cannot. Once we corrected this the sync completed without error.