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Error 0x81000036 Windows Backup: Fixes That Work

Guide 10-6496 · Updated · Step by step

Error 0x81000036 in Windows Backup stops your backup from completing and usually appears as a pop-up saying the backup failed. The fix is to reset the backup’s shadow copy storage, free up disk space, and check the Windows Backup service; this article walks through the exact steps for Windows 10 and 11.

What Error 0x81000036 Means

Windows Backup uses the Volume Shadow Copy Service (VSS) to snapshot files while you work. Error 0x81000036 is the code Windows reports when it cannot create or write to that shadow copy. It is not a sign of a failing hard drive or a virus; it is a storage or service problem that is usually fixable in a few minutes.

The error text often reads: “The backup did not complete. Error code: 0x81000036.� Some users see it after a Windows update, others after filling their drive to near capacity. The underlying cause is almost always one of three things: not enough free space for the shadow copy, the VSS service not running, or a corrupted shadow copy storage file.

Why Windows Backup Needs Shadow Copies

Windows Backup (the built-in tool in Settings > Update & Security > Backup, or Control Panel > Backup and Restore) creates a full image of your files and then incremental versions. To do this safely while you are using the computer, it uses VSS to make a point-in-time snapshot. That snapshot lives in a hidden system area called the shadow copy storage.

If that storage area is full, or if the VSS service is disabled, the backup engine cannot take the snapshot and throws error 0x81000036. The same code can appear when the backup target (an external drive or network location) does not have enough room for the snapshot plus the backup data.

Quick Fixes to Try First

  1. Restart the Windows Backup service. Press Win + R, type services.msc, and press Enter. Scroll to “Volume Shadow Copy,� right-click it, and choose Restart. Do the same for “Windows Backup� if present. Then try your backup again.
  2. Free up disk space. Shadow copies need at least 5–10% of your system drive free. Use Disk Cleanup (search “Disk Cleanup� in Start, select your system drive, and clean temporary files).
  3. Run the System File Checker. Open Command Prompt as Administrator and run sfc /scannow. This repairs corrupted system files that can interfere with VSS.

These three steps resolve a large share of 0x81000036 errors. If the error persists, move on to the deeper fixes below.

Reset the Shadow Copy Storage

Over time, the shadow copy storage can become fragmented or corrupted. Resetting it clears out old snapshots and gives VSS a fresh start. This does not delete your personal files; it only removes previous restore points and shadow copies.

  1. Open Command Prompt as Administrator.
  2. Type vssadmin list shadowstorage and press Enter to see current usage.
  3. To delete all existing shadow copies, type vssadmin delete shadows /all /quiet and press Enter.
  4. Resize the storage to a reasonable limit: vssadmin resize shadowstorage /for=C: /on=C: /maxsize=10GB (adjust the drive letter and size to your system).
  5. Reboot and try the backup again.

If the vssadmin command fails with “access denied,� make sure you are truly running as Administrator, not just a user with admin rights. Right-click Command Prompt and choose “Run as administrator.�

Check the Backup Target Drive

Error 0x81000036 can also mean the destination drive is full or formatted with a file system that does not support shadow copies. The backup target should be NTFS, not FAT32 or exFAT. To check, open File Explorer, right-click the drive, select Properties, and look at the “File system� line.

If the target is FAT32, you have two options: reformat it to NTFS (which erases the drive, so back up its contents first), or switch to a different external drive. Also ensure the target has at least as much free space as the data you are backing up, plus a little extra for the shadow copy.

Use the Windows Backup Troubleshooter

Microsoft provides a dedicated troubleshooter for backup and restore issues. In Windows 10 and 11, you can download the “Windows Backup Troubleshooter� from Microsoft’s official site (search “Windows Backup Troubleshooter download�). It automates the checks above and can fix service and registry issues.

If you prefer not to download anything, you can run the built-in Hardware and Devices troubleshooter: open Settings > System > Troubleshoot > Other troubleshooters (Windows 11) or Update & Security > Troubleshoot (Windows 10), and run “Hardware and Devices.� This is less targeted but sometimes catches driver issues that affect VSS.

When to Switch to File History or a Third-Party Tool

If error 0x81000036 persists after all these steps, the Windows Backup engine may be too damaged to repair easily. In that case, consider using File History (for personal files) or a third-party backup tool. File History is built into Windows and works differently from Backup and Restore; it is less prone to VSS errors.

To enable File History: Settings > Update & Security > Backup (Windows 10) or Settings > Accounts > Windows backup (Windows 11), then add a drive. It backs up files in your Libraries, Desktop, and Contacts folders automatically.

For a full system image, you can still use the “Create a system image� option in Control Panel, but if that also fails, a third-party tool that does not rely on VSS (like those that run a scheduled copy) may be a more reliable choice.

Frequently Asked Questions

Will I lose my files if I delete shadow copies?

No. Shadow copies are restore points, not your actual files. Deleting them only removes the ability to restore previous versions of files from before that point. Your current files remain untouched.

Why does the error appear after a Windows update?

Windows updates can change VSS service permissions or leave the service in a stopped state. Restarting the Volume Shadow Copy service and running sfc /scannow usually resolves update-related issues.

Can I ignore error 0x81000036 and still have a working backup?

No. The error means the backup did not complete, so you have no new backup. If you ignore it, you risk losing recent changes in a drive failure. Fix it or switch to an alternative backup method.

Does the error mean my hard drive is failing?

Not directly. It is a VSS or storage issue, not a hardware failure indicator. However, if you also see other signs like slow performance or bad sectors, run a disk check (chkdsk /f) to rule out hardware problems.

What is the difference between Windows Backup and File History?

Windows Backup creates a full system image that can restore the entire OS, while File History only copies your personal files. File History is more resistant to VSS errors because it uses a different mechanism. For most users, File History plus a system image is a good combination.

Can I use a network drive as a backup target?

Yes, but the network drive must be accessible and have enough space. Some network drives (especially NAS devices) do not support VSS properly, which can cause error 0x81000036. In that case, try a local external drive.

Related

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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