Fix DNS error 0x00002560 background loading

You boot a Windows DNS server, and the service starts fine. But when you try to do anything — update a record, run nslookup, or check the server properties — you get this message: "This operation is not allowed while the DNS server is loading zones in the background" with error code 0x00002560. The event log might show event ID 3150 with the same text. This usually happens right after a reboot or a service restart. The server appears stuck, but it's not crashed — it's hung on a single bad record it can't parse.

What's happening here

The DNS server reads zone files from %systemroot%\system32\dns during startup. It loads zones one at a time. When it hits a record that doesn't match the expected format — like a mangled IP address, an extra space, a missing parentheses, or a record type it doesn't recognize — it stops. It doesn't skip it. It just sits there, stuck on that record, and refuses any other operations until the zone load finishes. Which it never will, because it's waiting for you to fix that record.

I've seen this triggered by someone editing a zone file manually with Notepad and accidentally adding a stray character. Or by a replication glitch that introduced a bad entry. The real fix is to find that bad record and either fix it or comment it out.

How to fix it

Stop the DNS service. Open a Command Prompt as Administrator and run:
net stop dns
Wait for the "stopped successfully" message. If it doesn't stop, use sc query dns to check the state.
Back up the zone files. Go to C:\Windows\System32\dns. Copy the entire folder somewhere safe. This is your safety net if you delete the wrong thing.
Find the last file that was modified. Sort the folder by "Date Modified". Look for .dns files. The one that was modified last (or has a timestamp matching your server's last boot) is the most likely suspect. Zone files are named after the zone, like contoso.com.dns.
Open that file in Notepad. Right-click it, choose Open with Notepad. Don't use WordPad or any rich text editor — they'll add formatting and break things further.
Look for the line that doesn't look right. Scroll through. Normal records look like this:
www 3600 A 192.168.1.10
Bad records might show:
- An IP address with letters in it (like 192.168.1.abc)
- A missing TTL value
- Extra characters (like a stray comma or quotes)
- A record type the server doesn't know (like ABCD instead of A or MX)
- An empty line that actually has a hidden space
Comment out the suspicious line. Put a semicolon (;) at the start of that line. That tells the DNS server to ignore it. Don't delete it until you're sure it's not needed.
Save the file. Notepad will warn you it's a system file. Click Yes.
Start the DNS service. Back in the Command Prompt, run:
net start dns
It should start normally and not show the error anymore.
Test it. Open DNS Manager. Right-click the server and choose "Configure the Server". If it opens without error, you're good. Also run nslookup localhost 127.0.0.1 to confirm queries work.

If it still fails

If the error comes back after you start the service, you missed a bad record. Repeat steps 1-9, but this time look at every .dns file in the folder. The bad record might not be in the newest file. Also check the Cache.dns file — that's the root hints file. A corrupted root hint can cause the same behavior.

If you can't find anything wrong with the zone files, check the DNS server configuration logs. Look in %systemroot%\system32\dns\dns.log if verbose logging was enabled. It will tell you exactly which file and which line it was reading when it hung.

One more thing: if this server is a domain controller, the zones might be stored in Active Directory, not in files. In that case, the error is different — it's a replication issue, not a file format issue. You'd need to check AD replication health with repadmin /replsum and fix the partner server that's sending bad data. But for a standard file-backed DNS server, the fix above works 99% of the time.