Fix STATUS_DS_INVALID_ATTRIBUTE_SYNTAX (0xC00002A2) in Active Directory

What's Going On?

You're seeing error 0xC00002A2 with the message "The attribute syntax specified to the directory service is invalid". This usually pops up when you're running a synchronization tool like Azure AD Connect, or when someone tried to extend the AD schema with a custom attribute but got the syntax wrong. I've seen this most often after a third-party app pushed a schema extension without proper validation — had a client last month whose SharePoint install borked the schema and took down their whole sync for two days.

Here's the fix, starting with the quickest check and moving to the deep dive. Stop when the error goes away.

Level 1: Quick 30-Second Check

This won't solve it in every case, but it's worth ruling out a temporary glitch. Open Command Prompt as Administrator on a domain controller and run:

repadmin /syncall /AdeP

If you see replication errors tied to the same attribute, note the attribute name. Then run:

dcdiag /test:replications

If everything passes, move on. If you see failures specifically about an attribute syntax mismatch, you've found your culprit. But don't stop here — this is just a diagnostic step.

Level 2: 5-Minute Fix — Replicate and Reboot

Sometimes the error is due to a stale or corrupted attribute value that's stuck in a local copy. Force replication and restart the relevant service.

1. On your primary DC, run repadmin /syncall /force to push all pending changes.
2. Restart the Active Directory Domain Services service (net stop ntds then net start ntds) — this resets the attribute cache on that DC.
3. If you're using Azure AD Connect, restart its sync service (Restart-Service -Name ADSync in PowerShell).

Try your sync operation again. If the error is gone, you're done. If not, the problem is in the actual schema — time to dig in.

Level 3: Advanced 15+ Minute Fix — Schema Surgery

This is where we get into the weeds. The error 0xC00002A2 means a specific attribute in the schema has a syntax value that's not valid for its object class. Use LDP.EXE or ADSI Edit to find and fix it.

Step 1: Identify the Bad Attribute

Run this PowerShell command on a domain controller (elevated):

Get-ADObject -Filter {ObjectClass -eq 'attributeSchema'} -Properties * | Where-Object {$_.AttributeSyntax -notin @('2.5.5.1','2.5.5.2','2.5.5.3','2.5.5.4','2.5.5.5','2.5.5.6','2.5.5.7','2.5.5.8','2.5.5.9','2.5.5.10','2.5.5.11','2.5.5.12','2.5.5.13','2.5.5.14','2.5.5.15','2.5.5.16','2.5.5.17','2.5.5.18','2.5.5.19','2.5.5.20','2.5.5.21','2.5.5.22','2.5.5.23','2.5.5.24','2.5.5.25','2.5.5.26','2.5.5.27')} | Format-List Name,AttributeSyntax,LDAPDisplayName

This lists any attribute with an invalid syntax OID. If nothing shows, run a broader check — look for attributes that have a syntax but no attributeSyntax property set:

Get-ADObject -Filter {ObjectClass -eq 'attributeSchema' -and AttributeSyntax -eq $null}

If you find one, note the LDAPDisplayName. That's your troublemaker.

Step 2: Fix the Syntax

Open ADSI Edit. Connect to the Schema partition (CN=Schema,CN=Configuration,DC=yourdomain,DC=com). Navigate to the bad attribute. Right-click → Properties.

• Find attributeSyntax — set it to a valid OID. For a string attribute, use 2.5.5.12 (Unicode string). For an integer, 2.5.5.9.
• Check oMSyntax — for string, it should be 27; for integer 2; for boolean 1. A mismatch here also triggers this error.

TIP: If you're not sure what the original type should be, look at the application that created it. I've seen Exchange extensions use 2.5.5.8 (distinguished name) where someone later changed it to a string. That'll break everything.

Step 3: Force Schema Reload

After editing, on the DC where you made the change, run:

repadmin /syncall /force

Then restart the AD service:

net stop ntds && net start ntds

On all other DCs, force replication and restart as well. Then retest your sync.

Prevention — Don't Let This Happen Again

Always test schema extensions in a lab first. If you're extending the schema manually, use ldifde with validated LDIF files — never edit attributeSyntax or oMSyntax directly unless you know exactly what you're doing. And for Azure AD Connect, keep your schema up to date with the latest version — old versions sometimes create invalid attributes.

If you're still stuck after these steps, the issue might be deeper — like a corrupt partition. In that case, consider restoring from backup or contacting Microsoft Support. But 90% of the time, it's one bad attribute syntax value.