Fix ERROR_DS_DRA_RPC_CANCELLED (0X00002107) in AD Replication

What This Error Means

You're getting ERROR_DS_DRA_RPC_CANCELLED (0X00002107) on a domain controller. This happens when the replication request from one DC to another gets dropped mid-flight. The RPC call started but didn't finish.

I see this most often when there's a network blip, a firewall rule that's too strict, or a DNS problem that makes the destination DC unreachable mid-replication. It can also happen if the RPC service on the target DC crashes or gets restarted.

Don't panic. Most of the time this fixes with a simple retry. But if it keeps coming back, you need to dig deeper.

The Quick Fix (30 seconds) – Retry Replication

Sometimes the universe just hiccups. Try forcing replication again manually.

1. Open Active Directory Sites and Services on your source DC.
2. Go to Sites > your site > Servers > your DC > NTDS Settings.
3. Right-click the connection object to the DC that failed. Select Replicate Now.
4. Wait for the pop-up. If it says "Replication completed successfully," you're done. If it gives the same error, move to the next step.

If the GUI is sluggish, use the command line instead:

repadmin /syncall /AdeP

That forces replication with all partners. Check for errors in the output. If you see 0X00002107 again, keep going.

Moderate Fix (5 minutes) – Check DNS and Firewall

The most common cause of this error is DNS. Your DC can't find the target DC's IP address, or it gets the wrong one. Here's what to check:

1. On the source DC, open Command Prompt as Administrator.
2. Type nslookup <target-DC-fully-qualified-domain-name>. For example:
   nslookup dc2.contoso.com
   You should see the correct IP address of the target DC. If you get a timeout or a wrong IP, fix DNS first. That's the root cause.
3. Run dcdiag /test:dns. Look for any FAIL or WARN near the DNS section.

Next, check your firewall. RPC for AD replication uses dynamic ports (usually 49152-65535) plus port 135. If you have a hardware firewall or Windows Firewall with Advanced Security, make sure those ports are open between the DCs. A quick test is to temporarily disable the firewall on both DCs (in a test window, not in production without approval) and see if replication works. If it does, you found the problem. Re-enable the firewall and add the correct rules.

Real-world trigger: I've seen this when someone updated a firewall rule and forgot to allow RPC dynamic ports. The error popped up immediately after the change.

Advanced Fix (15+ minutes) – Dig Into RPC and Timeout Settings

If DNS and firewalls are clean, the issue is deeper. The RPC call is timing out or being canceled by a service restart.

Step 1: Check RPC Service

On the target DC, open Services.msc. Look for Remote Procedure Call (RPC). It should be running. If it's stopped, start it. Also check the RPC Endpoint Mapper service. Both need to be running.

Step 2: Increase RPC Timeout

Sometimes the default RPC timeout is too short for large replication packets. You can increase it in the registry. Be careful – back up your registry first.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters]
"Replicator RPC Timeout (seconds)"=dword:0000012c

That sets the timeout to 300 seconds (5 minutes). The default is 120 seconds. After adding this, restart the Active Directory Domain Services service (net stop ntds && net start ntds).

Step 3: Check for Stuck Replication Queues

Run this on the source DC:

repadmin /showrepl

Look for any pending or failed attempts. If you see repeated failures with 0X00002107, try clearing the replication queue:

repadmin /removehold <source-DC> <target-DC> <nc>

Replace <source-DC>, <target-DC>, and <nc> (naming context, like DC=contoso,DC=com) with your actual values. This forces a fresh replication attempt.

Step 4: Check Event Logs

On both DCs, open Event Viewer > Windows Logs > System. Filter by Source: NTDS Replication or Source: RPC. Look for events with ID 1126, 1655, or 1925. Those often give more detail about why the RPC was canceled.

Final Resort – Demote and Promote

If nothing works and replication is still broken after an hour of troubleshooting, demote the problem DC (remove AD DS role) and promote it again. This is nuclear but effective. Back up FSMO roles first. I've done this maybe 3 times in my career – it's rare but it works when the DC's AD database is corrupted.

Bottom line: Start with the quick retry. Then check DNS and firewall. Only go to registry changes if you're sure the network is clean. And always check the event logs – they tell you exactly what was happening when the RPC got canceled.