The short version
- 01Read the full name of the failing update in Update history before anything else.
- 02Check the recovery partition exists and has 250 MB free, using reagentc /info.
- 03Run Microsoft’s PowerShell resize script first — it is the safer of the two routes.
- 04Use Microsoft’s manual diskpart procedure only if the script cannot proceed.
- 05Run reagentc /enable if you stop partway, so WinRE is not left switched off.
- 06For any other update, run DISM /Restorehealth then sfc /scannow instead.
Start here
Read the update’s name, not just the code
0x80070643 is a generic “installation failed” code, so the fix depends entirely on which update produced it. If Windows Update names a Windows Recovery Environment update, the cause is almost certainly a recovery partition with too little room: Microsoft’s article for that update states it needs 250 MB of free space in the recovery partition, and Microsoft has published both a script and a manual procedure to enlarge it. If the code appears against ordinary cumulative updates instead, treat it as component-store corruption and run DISM and SFC.
Applies to: Windows 10 version 21H2 and 22H2, Windows 11 and Windows Server 2022, where Windows Update reports install error 0x80070643. The recovery-partition route applies to the Windows Recovery Environment updates specifically; the component-store route applies to everything else.
Which update is showing the code?
This code stopped being a rare curiosity in January 2024, when a Windows Recovery Environment update began failing on a very large number of otherwise healthy PCs. Those machines are not broken. Their recovery partitions were sized years earlier by an installer or an OEM that had no reason to leave room for a bigger WinRE image, and the update has nowhere to go. That is a completely different problem from a cumulative update failing with the same number, which is why the first step here is reading the name of the update rather than the code beside it.
The failing update mentions Windows Recovery Environment
Does the recovery partition have 250 MB free?
Check the partitionYou want the least risky fix
Can you run Microsoft’s script?
Run the scriptThe script refuses to run
Is the recovery partition right after the OS partition?
Resize by handIt’s a cumulative or feature update instead
Is the component store healthy?
Repair the store1. Find out what actually failed
Open Settings, then Windows Update, then Update history, and read the full name of the entry that failed. 0x80070643 is a general installation failure rather than a specific diagnosis, so the same number can mean a partition is too small, a component store is damaged, or an installer has fallen over. The name of the update is what separates those, and it takes ten seconds to look at.
If the failing entry is a Windows Recovery Environment update, you are in the common case and sections 2 to 4 are the whole answer. If it is a cumulative update, a .NET update or a driver, skip to section 5 — the recovery partition has nothing to do with it, and resizing partitions to fix an unrelated update would be an unnecessary risk.
It is also worth checking whether the failure repeats. Windows retries updates on its own schedule, and a single failed attempt that never recurs is not worth investigating. Chase the code when the same update has failed several times over several days.
Everything below is decided by the answer to one question: does the failing update mention the recovery environment? Do not skip the check.
2. Why the recovery environment update needs room
Microsoft’s article for the WinRE update describes what it does plainly: it automatically applies the Safe OS Dynamic Update to the Windows Recovery Environment on a running PC and installs improvements to Windows recovery features. To do that it has to write a larger recovery image into the recovery partition, and Microsoft states the update requires 250 MB of free space in that partition to install successfully.
The same article lists the conditions under which the update will not be offered at all, and insufficient free space in the recovery partition is the first of them — alongside a WinRE that has already been updated manually, a WinRE already at or above the required version, and a machine with no recovery partition. That list is a useful sanity check: if you have no recovery partition, there is nothing to enlarge.
You can see the current state from an elevated Command Prompt with reagentc /info, which reports whether WinRE is enabled and where its image lives. Disk Management will show you the recovery partition and its size, though it will not let you resize it — which is exactly why Microsoft published a separate procedure.
Recovery partition present but small
The normal case. Enlarge it using section 3 or section 4.
No recovery partition at all
The update is not offered rather than failing. There is nothing to resize.
3. Microsoft’s script, which is the safer route
Microsoft published a PowerShell script specifically to automate this, and it is the route to try first. The article covering it explains that the script increases the size of the recovery partition to enable servicing of the Windows Recovery Environment, extending it by 250 MB — the amount the update needs. Run PowerShell as Administrator and follow the article’s instructions rather than improvising.
The script has one hard limit worth knowing before you start: it cannot proceed if the recovery partition is not immediately after the OS partition. That layout is common on machines that have been repartitioned, dual-booted or restored from an image, and it is not a fault — it simply means the space next to the recovery partition is not the OS partition’s to give.
The script writes a backup directory while it works, and Microsoft’s instruction is explicit: do not interrupt the execution or restart your system while it runs. Once it has finished successfully that backup directory is no longer needed and can be deleted. Let it finish, then re-check Windows Update.
Run the script before attempting anything with diskpart. It does the same job with far fewer opportunities to make an unrecoverable mistake.
4. The manual resize, and the order that matters
Microsoft’s manual procedure exists for the cases the script will not handle. It has the same prerequisite — the recovery partition must be located immediately after the OS partition — and the article tells you to verify that before proceeding. The sequence is to check the current state with reagentc /info, disable WinRE with reagentc /disable, shrink the OS partition, delete and recreate the recovery partition, then re-enable WinRE with reagentc /enable.
The shrink and rebuild happen in diskpart: list disk, sel disk with the OS disk index, list part, sel part with the OS partition index, then shrink desired=250 minimum=250. You then select the WinRE partition and run delete partition override, which is the point of no return and the reason to have a backup of anything you care about before you begin.
Recreating the partition depends on the partition style, which list disk tells you — an asterisk in the Gpt column means GPT, and no asterisk means MBR. On GPT the command is create partition primary id=de94bba4-06d1-4d40-a16a-bfd50179d6ac followed by gpt attributes =0x8000000000000001. On MBR it is create partition primary id=27. Either way you then format the partition as NTFS with the label Windows RE tools, check the result with list vol, and exit.
Microsoft’s safety net is the last line of the article and the most important one: if creation failed, or you decide you do not want to extend the WinRE partition after all, run reagentc /enable to re-enable WinRE. Do not leave the machine with WinRE switched off — that is the recovery environment you would want if something went wrong later.
delete partition override does exactly what it says. Read Microsoft’s article end to end before running any of it, and make sure your files are backed up.
5. When it is not the recovery environment update
For any other update, 0x80070643 is just a failed installation and the partition has nothing to do with it. The standard route is the component-store repair Microsoft documents for update failures generally: open an elevated Command Prompt, run DISM.exe /Online /Cleanup-image /Restorehealth, wait for it to finish, then run sfc /scannow, then retry Windows Update.
DISM repairs best when it can reach Microsoft Update to fetch replacement files. Microsoft notes that if the machine cannot connect you can point it at a known-good Windows installation instead, using the /Source switch with /LimitAccess. On a home machine the online route is almost always the right one, and the offline route is worth reaching for only when the machine is genuinely isolated.
DISM writes what it found and fixed to %windir%\Logs\CBS\CBS.log. If the restore operation reports success and the update still fails, that log names the specific component that is still broken — which is the difference between guessing and knowing when you escalate.
6. What to establish before asking for help
Four facts settle almost every version of this. Which update is failing, by its full name. Whether a recovery partition exists and how much free space it has. Whether Microsoft’s resize script ran, and what it said if it refused. And whether DISM and SFC completed cleanly. Anyone helping you will ask for those, and having them turns a vague report into a specific one.
Be honest about the machine’s history too, because it explains the awkward cases. A disk that has been repartitioned, restored from an image, migrated to a larger drive or dual-booted is much more likely to have its recovery partition somewhere other than immediately after the OS partition — which is precisely the layout both Microsoft procedures decline to handle.
When you contact Microsoft, say which update failed, what reagentc /info reports, what Disk Management shows for the recovery partition’s size and position, whether the script or the manual procedure was attempted and where it stopped, and the result of DISM and SFC. Those five answers separate a small partition from a misplaced one from a damaged component store.
Frequently asked questions
What does error 0x80070643 mean in Windows Update?
It means an installation failed, and nothing more specific than that. The useful information is which update failed. A Windows Recovery Environment update failing with this code almost always means the recovery partition is too small — Microsoft states that update needs 250 MB of free space there. Any other update failing with it points at component-store corruption instead.
Why does the WinRE update keep failing on my PC?
Because the recovery partition was sized before the update existed and has less than the 250 MB of free space Microsoft says the update requires. The machine isn’t faulty; the partition is simply too small for a larger recovery image. Enlarging it with Microsoft’s script, or manually if the script can’t, resolves it.
Is there a safe way to resize the recovery partition?
Microsoft’s PowerShell script is the safer route and should be tried first — it extends the recovery partition by 250 MB automatically. Run PowerShell as Administrator and don’t interrupt it or restart while it runs. The manual diskpart procedure involves deleting and recreating the partition, so keep that as the fallback.
Why won’t Microsoft’s resize script run on my machine?
Most often because the recovery partition is not immediately after the OS partition, which the script requires. That layout is common on disks that have been repartitioned, restored from an image or dual-booted. Microsoft’s manual procedure has the same prerequisite, so in that situation neither published route applies directly.
Can I just ignore the failing recovery environment update?
You can, and the PC will keep working — but the update exists to improve the recovery environment, including its security, so leaving it uninstalled leaves that gap open. If you decide to stop partway through the manual procedure, the one thing you must do is run reagentc /enable so WinRE is switched back on.
What if 0x80070643 appears on a normal cumulative update?
Treat it as component-store corruption. From an elevated Command Prompt run DISM.exe /Online /Cleanup-image /Restorehealth, then sfc /scannow, then retry the update. DISM records what it found in %windir%\Logs\CBS\CBS.log, which names the specific component if the repair doesn’t complete.
Sources and review notes
Checked on . Compiled by Glitchary from Microsoft’s support and Learn documentation. Recovery Environment updates are reissued periodically under new KB numbers, and partition procedures carry a real risk of data loss — read Microsoft’s current article for your Windows version end to end before running any of the commands described here, and back up first. Glitchary is independent of Microsoft.
- Microsoft: Windows Recovery Environment update for Windows 10, version 21H2 and 22H2 (KB5034441)
- Microsoft: KB5035679 — instructions to run a script to resize the recovery partition
- Microsoft: KB5028997 — instructions to manually resize your partition to install the WinRE update
- Microsoft: fix Windows Update corruptions and installation failures