Fixes / Windows · Checked September 30, 2026

Windows Update error 0x80070643: what it means and how to fix it

Short answer

Error 0x80070643 (ERROR_INSTALL_FAILURE) means an update's installer stopped before it finished. First check Update history to see which update failed. If it is a Windows Recovery Environment update on Windows 10, such as KB5034441, the recovery partition needs 250 MB of free space. Microsoft's KB5028997 steps show how to resize it. For any other update, restart and run the Windows Update troubleshooter.

What this message means

0x80070643 is a generic code for ERROR_INSTALL_FAILURE. It tells you an installer ran and failed, but not why. The underlying cause depends on which update failed. With Windows Recovery Environment (WinRE) updates on Windows 10, the real problem is usually CBS_E_INSUFFICIENT_DISK_SPACE: the small recovery partition doesn't have the 250 MB of free space the new recovery image needs. With Microsoft Defender, .NET Framework or cumulative updates, the usual causes are a damaged update cache, corrupted system files, a broken .NET installation or interference from third-party antivirus. Some recent WinRE updates also show this code even though they installed correctly.

Common causes

Cause	How to tell
The recovery (WinRE) partition is too small for a Windows Recovery Environment update (Windows 10 21H2/22H2, for example KB5034441)	The failed item in Update history is named "Windows Recovery Environment update" or "Security Update for Windows (KB5034441)". It fails again on every retry while other updates install normally. In Disk Management, the Recovery partition is about 500 MB or smaller.
A false failure report on a WinRE update that installed while another update was waiting for a restart (for example KB5057589, April 2025)	The WinRE update shows 0x80070643 once, then shows as installed or disappears after the next restart and daily scan. The PC behaves normally.
The Microsoft Defender Antivirus platform or definition update failed (often KB4052623 or KB2267602)	The failed entry mentions Microsoft Defender Antivirus, or "Security Intelligence Update". Third-party antivirus is often installed alongside Defender.
The .NET Framework installation is damaged	The failed update is named "Cumulative Update for .NET Framework". Some apps that depend on .NET may also refuse to start or install.
The Windows Update cache (SoftwareDistribution folder) is corrupted, or system files are damaged	Several different updates fail with 0x80070643 or other 0x8007 codes, often after a power cut or a forced shutdown in the middle of an update.

How to fix it

1. Find out which update failed, then restart and retry

Windows 11: open Settings > Windows Update > Update history. Windows 10: open Settings > Update & Security > Windows Update > View update history.
Note the name and KB number of the entry marked "Failed to install" with 0x80070643.
Restart the PC with Start > Power > Restart (not Shut down) so any pending update finishes.
Go back to Windows Update and select Check for updates.
If the failed item is a Windows Recovery Environment update and now shows as installed, the error was a false report and you are done.

2. Run the Windows Update troubleshooter

Windows 11: Start > Settings > System > Troubleshoot > Other troubleshooters. Next to Windows Update, select Run.
Windows 10: Start > Settings > Update & Security > Troubleshoot > Additional troubleshooters > Windows Update > Run the troubleshooter.
Let it apply the fixes it finds, restart, and check for updates again.

3. Update Microsoft Defender directly (when the failed update is a Defender update)

Open the Start menu, type Windows Security and open it.
Go to Virus & threat protection. Under Virus & threat protection updates, select Protection updates.
Select Check for updates and wait for it to finish.
If you use a third-party antivirus, turn it off temporarily and retry the update in Windows Update. Turn it back on afterwards.

4. Reset the Windows Update cache and repair system files

Open the Start menu, type cmd, right-click Command Prompt and choose Run as administrator.
Run these commands one at a time: net stop wuauserv, then net stop bits, then net stop cryptsvc.
Run: ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
Run: net start wuauserv, then net start bits, then net start cryptsvc.
Run: DISM /Online /Cleanup-Image /RestoreHealth. When it finishes, run: sfc /scannow
Restart and check for updates again. If a .NET Framework update still fails, run Microsoft's .NET Framework Repair Tool and retry.

5. Enlarge the recovery partition for WinRE updates (KB5028997 method)

Windows 10 21H2/22H2 when a Windows Recovery Environment update (such as KB5034441) keeps failing. Back up your data first. Deleting the wrong partition in diskpart causes data loss.

In an administrator Command Prompt, run reagentc /info and note the WinRE location (disk and partition number). Then run reagentc /disable.
Run diskpart, then list disk and sel disk <OS disk number>, then list part and sel part <Windows (C:) partition number>. Then run shrink desired=250 minimum=250
Run sel part <recovery partition number>, then delete partition override
On a GPT disk (an asterisk in the Gpt column of list disk), run: create partition primary id=de94bba4-06d1-4d40-a16a-bfd50179d6ac and then gpt attributes=0x8000000000000001. On an MBR disk, run: create partition primary id=27
Run format quick fs=ntfs label="Windows RE tools", then list vol to confirm the new volume, then exit.
Run reagentc /enable, then reagentc /info to confirm Windows RE status is Enabled.
Go to Settings > Update & Security > Windows Update and select Check for updates to install the WinRE update.

Next time, skip the search

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Still not fixed?

If the WinRE update still fails, check whether the recovery partition sits before the Windows partition on the disk (reagentc /info plus Disk Management will show this). Microsoft's resize steps only work when the recovery partition comes after it. In that case, a third-party partition tool or a clean reinstall is the realistic route. For Defender, .NET or cumulative updates that keep failing, download the exact KB from the Microsoft Update Catalog and install it manually, or run an in-place repair with the Windows 11 or Windows 10 installation media (choose "Keep personal files and apps"). On a work or school PC, contact your IT department, because update policies and BitLocker may be managed centrally. Before touching partitions, save your BitLocker recovery key.

Questions people ask

Is it safe to ignore error 0x80070643?

For the April 2025 WinRE updates (such as KB5057589), Microsoft says the message "is not accurate and does not impact the update or device functionality", so you can ignore it. For KB5034441, ignoring it leaves a BitLocker bypass vulnerability unpatched. The risk is low if you don't use BitLocker, and resizing the partition fixes it.

Why does KB5034441 keep failing with 0x80070643?

It needs 250 MB of free space in the recovery partition, and many Windows 10 PCs have a partition of about 500 MB that is already nearly full. Microsoft has not released an automatic fix for Windows 10, so the partition has to be resized manually.

Will deleting and recreating the recovery partition erase my files?

Not if you follow the steps exactly. Only the small recovery partition is deleted, and 250 MB is taken from the free space on C:. Picking the wrong partition number in diskpart will destroy data, though, so back up first.

Does 0x80070643 mean my PC has a virus?

Almost never. It is a generic install failure code. It shows up most often with WinRE, Defender and .NET updates, and malware is rarely the cause.

Does this error happen on Windows 11 too?

Yes, mainly with Defender, .NET Framework and cumulative updates. On Windows 11, fix it with the troubleshooter and the cache reset rather than by resizing partitions.

Sources

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