PEERDIST_ERROR_ALREADY_EXISTS (0x00000FDA) Fix

Cause 1: The file is already in the Peer Distribution cache

This is the most common reason you're seeing 0x00000FDA. Peer Distribution (also called Delivery Optimization in Windows 10/11) caches files it downloads from Microsoft or other peers. When a program or Windows Update tries to add the same file again, it throws this error because the file's already there.

You'll usually see this when running a script or tool that manually triggers a Peer Distribution download, or if you're working with a system that uses DLLs like peerdist.dll or PeerDistSvc.dll directly. It's safe to ignore in most cases, but if it's blocking something, here's how to fix it.

Fix: Clear the Peer Distribution cache

1. Press Windows Key + R to open the Run dialog.
2. Type services.msc and hit Enter. The Services window opens.
3. Scroll down until you find Peer Name Resolution Protocol and Peer Networking Grouping and Peer Networking Identity Manager and Delivery Optimization. You might not see all of them — that's okay.
4. Right-click Delivery Optimization and select Stop. Wait for the status to change to blank (Stopped).
5. Open File Explorer and go to C:\Windows\ServiceProfiles\NetworkService\AppData\Local\PeerDistPub. If you can't see it, you might need to check Show hidden files in File Explorer's View tab.
6. Delete everything inside that folder. Don't delete the folder itself, just the files inside.
7. Go back to Services, right-click Delivery Optimization, and select Start.

After doing this, the error should stop. Try running your command again. If it still shows up, move to the next cause.

Cause 2: The Peer Distribution service is corrupted or stuck

Sometimes the service itself gets into a weird state. It might think the cache is full, or it might be holding onto a corrupted entry that won't clear even after you delete the files. I've seen this happen after a failed Windows Update or after using a peer-to-peer update tool that crashed midway.

This fix is about resetting the service itself, not just the cache.

Fix: Disable and re-enable Peer Distribution

1. Open Services again (Win + R, type services.msc).
2. Find Delivery Optimization. Right-click it and select Properties.
3. Click Stop if it's running. Then change the Startup type dropdown to Disabled.
4. Click Apply, then click OK.
5. Restart your computer. Yes, a full reboot. You need to clear any stuck handles.
6. After the restart, go back to Delivery Optimization Properties and change the startup type back to Automatic (or Manual — either works).
7. Click Apply, then click Start to fire it up again.

This forces Windows to rebuild the service state from scratch. The error should be gone after that.

Cause 3: Another service or tool is blocking Peer Distribution

Less common, but real. Some third-party antivirus tools (especially McAfee and Norton) or firewall software can block Peer Distribution's ability to write to its cache. When that happens, the service tries to add a file, fails to save it properly, then sees the file as already existing because of a half-written entry. You get that 0x00000FDA error.

Also, if you're running any script, PowerShell command, or custom tool that directly calls PeerDistClientAddContentInformation or similar functions from PeerDist.dll, the same error can pop up if the tool tries to add duplicate info without checking first.

Fix: Temporarily disable third-party security software

1. Locate your antivirus or firewall icon in the system tray (near the clock).
2. Right-click it and look for an option like Disable or Pause protection. Choose a short period like 10 minutes or until reboot.
3. Try your command or operation again. If the error goes away, you've found the culprit.
4. Add an exception in your security software for C:\Windows\System32\PeerDistSvc.dll and C:\Windows\System32\peerdist.dll to prevent this in the future.

If you're writing a script that calls the Peer Distribution API, check your code to make sure you're not trying to add the same content hash twice. A simple check using PeerDistClientGetInformation before adding can avoid this.

Quick-reference summary table

One last thing — if you're only seeing this error in logs and nothing's actually broken, just leave it alone. Peer Distribution is designed to handle this silently. Only go through these fixes if the error is actively causing a problem.