Fix Volume Snapshot Merge Conflict Error 0x80042308 on Windows

Quick Answer for Pros

Run vssadmin list writers in an admin command prompt, check for failed writers (like System Writer), then restart the Volume Shadow Copy service and the software that owns the failed writer.

Why This Happens

I ran a help desk for years, and this error tripped me up the first few times. The Volume Snapshot Merge Conflict error (0x80042308) pops up when the Volume Shadow Copy service (VSS) can't merge an existing snapshot with a new one. Windows uses VSS to create consistent backups—think System Restore points, backup software like Acronis or Veeam, or even Windows Backup itself. When a snapshot merge fails, it's almost always because a VSS writer—a piece of software that tells VSS how to handle its data—is stuck or corrupted.

Common triggers: you run a backup after a failed software update, you have multiple backup tools installed (like both Windows Backup and a third-party tool), or you recently uninstalled a program that didn't clean up its VSS writer.

Fix Steps

Open an admin command prompt. Press Win + X, choose Terminal (Admin) or Command Prompt (Admin).
List VSS writers. Run vssadmin list writers. Look for any writer with a state of "Failed" or "Stable" with an error. The System Writer and SQL Writer are common culprits.
Restart the VSS service. Run net stop vss then net start vss. This clears transient hiccups.
Restart the failing writer's service. For System Writer, run net stop cryptsvc then net start cryptsvc. For SQL Writer, restart the SQL Server service via services.msc.
Retry the backup. Run your backup tool again. If the error's gone, you're done.

If the Main Fix Fails

Sometimes the writer doesn't restart cleanly. Here's what I do next.

Reset VSS Storage

Run vssadmin delete shadows /all to delete all shadow copies. Then vssadmin resize shadowstorage /for=c: /on=c: /maxsize=10GB to set a fresh storage limit. Don't skip the resize—default limits can cause future merge conflicts.

Re-register VSS Components

In an admin command prompt, run these in order:
cd /d %windir%\system32
regsvr32 /s vssui.dll
regsvr32 /s vss_ps.dll
regsvr32 /s swprv.dll
regsvr32 /s es.dll
regsvr32 /s ole32.dll
regsvr32 /s oleaut32.dll
Then reboot and try again.

Check for Conflicting Software

If you have two backup tools (like Windows Backup and Macrium Reflect) or an antivirus with backup features, uninstall one. I've seen Norton and Acronis fight over VSS writers more times than I can count.

Prevention Tip

Limit your backup tools to one that handles snapshots. Before uninstalling software, check if it has a VSS writer—uninstallers often leave writers behind. Use vssadmin list writers after uninstalling a big app like SQL Server or Exchange. If you see a left-behind writer, use regsvr32 /u on its DLL if you can find it, or use a dedicated tool like VSSAdmin to disable it. And please, don't let shadow storage auto-grow on system drives—set a cap. I use 10GB on a typical Windows machine. That's enough for a few restore points without choking the merge process.

One last thing: if you're running Windows 11 22H2 or later, there's a known bug where the System Writer fails after a cumulative update. The fix is to install the latest Windows update (KB5023778 or newer). Yes, it's that simple—but only if you're on that specific build.