Directory Sync Error

Question

I received an error "An ‎Azure AD‎ cloud ‎user‎ and an on-premises ‎user‎ have identical ‎Proxy address‎ values of ‎smtp:****@domain.com‎**. Attribute values must be unique to each ‎user‎. To fix this, decide which ‎user‎ should use the attribute, then change or remove the identical attribute from the other ‎user‎. You can also delete the entire cloud ‎user‎"

In my AD I disabled the user's account and manually renamed the UPN and Proxy Address from SMTP: ******@domain.com. I then applied the existing smtp: ******@domain.com to the existing shared mailbox as another proxy. Meaning, the shared mailbox has its own SMTP: ******@domain.com and I inserted the smtp: ******@domain.com. However, by doing this, the information use's UPN in the AAD didn't changed to the updated SMTP: ******@domain.com. Some attributes changed in AAD but not the UPN. This is why I am getting the Proxy or UPN conflict. Since the existing SMPT was renamed, is it okay to use the original SMTP and reapply this to the shared mailbox as proxy email, smtp: ******@domain.com? What is the resolution to prevent the conflict? The suggestion above is to change or remove the identical attributes...? We want to keep the original UPN as another proxy address in the Shared Mailbox. Your input is greatly appreciated, thanks.

Answer 1

Hi @A_Lop ,

I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to "Accept " the answer.

Issue:

When synchronizing users you received the error, "An ‎Azure AD‎ cloud ‎user‎ and an on-premises ‎user‎ have identical ‎Proxy address‎ values of ‎smtp:****@domain.com‎**. Attribute values must be unique to each ‎user‎. To fix this, decide which ‎user‎ should use the attribute, then change or remove the identical attribute from the other ‎user‎. You can also delete the entire cloud ‎user‎"

Solution:
You removed the proxy address from the shared mailbox, let the attributes update in Azure AD which also cleared the proxy/UPN attribute conflict after 20 minutes. Once cleared, you re-added the original UPN to the shared mailbox. You also manually changed the UPN in Azure AD since this doesn't change automatically. After adding, there were no errors in Azure AD Connect.

If you have any other questions or are running into more synchronization issues, please let me know.

Thank you again for your time and patience throughout this issue.

Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.

Answer 2

What I did to fix the issue was to remove the proxy address from the shared mailbox. Let the attributes update in AAD which also cleared the proxy/UPN attribute conflict after at least 20 minutes. Once cleared, I then re-added the original UPN to the shared mailbox. I also had to manually change the UPN in AAD as this didn't change automatically. After adding, there's no error so far shown in M365 Azure connect.