What you’re seeing
- Entra Connect Health or the sync error report lists 'AttributeValueMustBeUnique' for one or more users.
- Alert emails warn about a duplicate ProxyAddresses or UserPrincipalName value.
- A new hire's account exists in Active Directory but never appears in Microsoft 365.
- Changes such as a name or email update made on-premises never reach the cloud account.
- The conflicting object can't be found easily, because it's a contact, group or deleted user.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- Two objects claim the same email alias, often because an old address wasn't removed from a former user.
- A cloud-only account or contact was created with the same UPN or email as the synced user.
- A shared mailbox, distribution group or mail contact already holds that address.
- A recently deleted user in Entra ID still reserves the address while it sits in the deleted items.
- Typos or copy-paste errors in attribute editing gave two users the same value.
Why it matters
When sync fails, a new employee may start without a working mailbox or Teams access, and changes to existing users silently stop flowing to the cloud. Departing staff may not be disabled in Microsoft 365, which is a real security risk. Because the conflict is often with an object nobody remembers, the error can sit unresolved for months, quietly piling up. Mail meant for one person can also be delivered to the wrong mailbox while the duplicate exists.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Why can't we find the conflicting account?
The duplicate is often not a user at all but a contact, group, shared mailbox or recently deleted object. Those don't show up where people usually look.
Does this affect other users?
Usually only the objects involved in the conflict, but sync errors tend to accumulate. Reviewing them all at once helps prevent surprises later.
Can AskTechGurus resolve sync errors remotely?
Yes. A certified US engineer traces the conflicting object and resolves the sync error over a secure remote session, often in a single session. It starts at $99 and you pay only when it's resolved.