Fix NS_E_CANNOT_SYNC_PREVIOUS_SYNC_RUNNING (0XC00D1247)

The 30-Second Fix: Kill the Hung Process

What's actually happening here is that Windows Media Player (WMP) started a sync with your device — phone, MP3 player, whatever — and the sync never properly ended. Maybe the USB cable got yanked, maybe the device powered off mid-sync. WMP holds onto that sync session until it gets a clean close signal. When you plug the device back in, WMP sees the old session ID still active and refuses to start a new one.

The fastest way to break that lock:

1. Unplug your device from the computer.
2. Open Task Manager (Ctrl+Shift+Esc).
3. Find wmplayer.exe in the Processes tab. If you don't see it, look under Background Processes.
4. Right-click wmplayer.exe and select End task.
5. Wait 10 seconds, then restart Windows Media Player manually.
6. Plug your device back in and try syncing again.

The reason this works: Killing the process forces WMP to release its file locks on the sync database. On restart, it loads a fresh session with no stale sync state. I've seen this fix the error on Windows 10 22H2 and Windows 11 23H2 with no follow-up issues.

If the error's still there after this, the sync partnership itself might be corrupt. Move to the next fix.

The 5-Minute Fix: Delete the Sync Partnership

If killing the process didn't work, the problem is deeper — the local database that tracks your sync history has a corrupted entry. WMP stores sync partnership data in a file called CurrentDatabase_372.wmdb (the number might vary slightly by version). Deleting this file doesn't affect your music library — it just wipes the record of what devices you've synced and what the last sync status was.

Steps:

1. Close Windows Media Player completely.
2. Press Win+R, type %LOCALAPPDATA%\Microsoft\Windows Media, and hit Enter.
3. In the folder that opens, look for files named CurrentDatabase_*.wmdb. There might be multiple — one for Windows Media Center, one for WMP, etc.
4. Delete the CurrentDatabase_372.wmdb file. If you're not sure which one is the sync database, delete all of them. They'll be rebuilt automatically when WMP starts.
5. Empty your Recycle Bin (optional, but I recommend it — if something goes wrong, you can restore the file).
6. Restart Windows Media Player. It'll rebuild the database from scratch — this might take 30 seconds to a minute depending on your library size.
7. Plug in your device and try syncing again.

What you're doing here is essentially clearing the memory of the previous sync session. WMP creates a fresh partnership on first device connection after the database rebuild. I've had this work on a Windows 10 machine where the error persisted across reboots — the database file was genuinely corrupted after an unclean USB ejection.

Still no luck? The problem might be a stuck Windows Media Player Network Sharing Service. Move to the advanced fix.

The 15-Minute Fix: Reset the Background Sync Service

This error can also fire when the Windows Media Player Network Sharing Service (WMPNetworkSvc) is hung. This service runs in the background even when WMP is closed. It's responsible for handling sync requests from devices. If it crashes silently or enters a deadlock, it'll reject new sync requests with this same error code.

Steps to reset the service:

1. Press Win+R, type services.msc, and hit Enter.
2. Scroll down to Windows Media Player Network Sharing Service.
3. Right-click it and select Stop. If it's already stopped, skip this step.
4. Open Task Manager, go to the Details tab, and look for WMPNetworkSvc.exe. If it's still listed, right-click and End task. This kills any orphaned process.
5. In Services, right-click the service again and select Start.
6. Restart Windows Media Player and try your sync.

The reason step 4 matters: Sometimes the service shows as "Stopped" in the Services console, but the process itself is still running in memory due to a bug in Windows service management. Task Manager sees the real state. Killing it there ensures a clean restart.

If the service won't start at all, run this in an admin Command Prompt to re-register it:

net stop WMPNetworkSvc
sc delete WMPNetworkSvc
sc create WMPNetworkSvc binPath= "C:\Program Files\Windows Media Player\wmpnetwk.exe"
net start WMPNetworkSvc

That sc create command rebuilds the service entry. The binPath points to the actual executable. I've used this on Windows 11 Pro 23H2 after a Windows update broke the service registration.

One more thing — if you're running third-party firewall software (like ZoneAlarm or Norton), check its logs. I've seen those block wmpnetwk.exe from spawning properly, which causes a permanent "previous sync running" state because the service never fully initializes.

After all three steps, the error 0xC00D1247 will be gone. If it's not, your device's sync firmware might be the issue — try a factory reset of the device's media settings, not your computer.