Fix SXS Duplicate Assembly Name Error 0x000036CB

What's happening when you see this error

You're trying to install something—maybe a Windows update, maybe a third-party app—and you get hit with ERROR_SXS_DUPLICATE_ASSEMBLY_NAME (0x000036CB). Frustrating, right? The system sees two assemblies that claim to be the same name but have different version numbers. Windows throws up its hands because it can't decide which one is correct. I've seen this most often after a failed update or after uninstalling a program that didn't clean up after itself.

The fix: clean the WinSxS store

Skip the registry editors and third-party cleaners. The real fix is to force Windows to tidy up its own side-by-side cache. Here's how.

1. Open Command Prompt as Administrator. Hit the Windows key, type cmd, right-click Command Prompt, and choose "Run as administrator." Click Yes if UAC pops up.
2. Run the DISM cleanup command. Type this and press Enter:
   DISM /Online /Cleanup-Image /ScanHealth
   This checks if the component store has corruption. Wait 2–5 minutes. You'll see "No component store corruption detected" or a percentage bar.
3. Now run the restore health command. Type this and press Enter:
   DISM /Online /Cleanup-Image /RestoreHealth
   This fixes what it found. Could take 10–20 minutes. Don't close the window. You'll see "The restore operation completed successfully." If it fails, you might need to point it to a known-good source—let me know in the comments if it does.
4. After DISM finishes, clean up old versions. Type this and press Enter:
   DISM /Online /Cleanup-Image /StartComponentCleanup
   This removes superseded components. Takes another 5–10 minutes. You won't lose anything important—these are old backups of assembly files.
5. Reboot your machine. Restart, then try your original install or update again. The error should be gone.

Why this works

Windows stores multiple versions of the same assembly in C:\Windows\WinSxS. Normally that's fine—it keeps compatibility for older apps. But sometimes a component gets corrupted or duplicated improperly (like from a failed update rollback). The DISM commands force Windows to check each assembly manifest against what's actually on disk, then merge or delete conflicting entries. The StartComponentCleanup flag specifically targets old, unneeded versions. I've used this on dozens of machines—it's the most reliable fix because it uses Microsoft's own repair tools.

Less common variations of this error

Sometimes the same error pops up during Windows Update, not during manual installs. If that's you, try these steps instead:

• Stop the Windows Update service. Open Command Prompt as admin, type net stop wuauserv, then net stop bits. That stops the update background services.
• Rename the SoftwareDistribution folder. Type ren C:\Windows\SoftwareDistribution SoftwareDistribution.old. This wipes the temporary update files—Windows recreates them fresh.
• Reboot and retry updates. Start the services again with net start wuauserv and net start bits, then check for updates.

Another variation: the error shows up when launching a specific program (like an older game or business app). That's a signed assembly mismatch. In that case, you need to reinstall the Visual C++ redistributable packages. Uninstall all of them from Control Panel, then download and install the latest from Microsoft's site for both x86 and x64. Reboot, then install your program again.

How to prevent this from coming back

This error usually comes from bad update practices or sloppy uninstalls. Here's what I tell my techs:

• Always install updates one at a time. If you batch-install, a single failure can corrupt the SxS store. Let each update finish before starting the next.
• Never force-close a Windows update. If it's stuck, use the Windows Update Troubleshooter instead of killing the process.
• Uninstall programs through the official uninstaller. Don't just delete folders—that leaves assembly references behind. Use "Add or Remove Programs" and reboot after each uninstall.
• Run DISM /Online /Cleanup-Image /StartComponentCleanup once a month. Keeps the SxS store lean. I do this on my own PC and haven't seen this error in years.

If none of this works, you might have deeper system file corruption. Run sfc /scannow from an admin command prompt. If it finds files it can't repair, you're looking at a repair install of Windows—but that's a last resort. Try the steps above first.