How do I fix the Data Validation Failure error when syncing with Azure AD?

Question

Active Directory

Synchronization with Azure AD is enabled on the domain controller. After the next synchronization, in the "Azure" portal in the "Azure Active Directory Connect Health" section, a synchronization error was detected for the "User" object of type "Data Validation Failure". I also looked at the logs for this error in "Synchronization service manager on Azure", writes: Unable to update this object in Azure Active Directory, because the attribute [userPrincipalName], is not valid. Update the value in your local directory services.
When moving to Azure, the domain in UserPricipalName was changed in the accounts from "domen.local" to "domen.ru" and there were no problems in the accounts, except for this one. At the same time, changing the domain in the UserPricipalName of the problem account back to "
Colleagues who faced this problem, please help with a solution.