Windows Update Failed? Find Your Error Code First

Windows Update has stopped on a long hex number. The button just says Retry. You have pressed it four times, restarted twice, and the same code comes back every time.

I want to save you the generic advice. That number is not decoration. It names the fault, and most of the codes point somewhere specific.

Find yours below. The codes are grouped by what they mean, not by how they are spelled, so look for the family if yours is not listed by name.

One warning first. The most searched update error is missing from Microsoft's own list, and the code it hands you names the wrong problem.

0x80070643, the one that is not telling you the truth

If this is your code, read this section before you touch anything, and read the one after it before you run a single command.

The code translates to ERROR_INSTALL_FAILURE. That sounds like the update itself failed. It usually means something else. A small hidden partition on your drive has no room in it.

It appears most often on KB5034441, the Windows Recovery Environment update. The update stages a file into your recovery partition. That partition is typically around 500 MB. The file no longer fits.

⛔ Microsoft's own explanation is that the error code is wrong, not that your install failed. Its wording is that this "may occur due to a problem in the error code handling routine".

And instead of a disk space message, "you may encounter the following error message when there is insufficient disk space: 0x80070643 – ERROR_INSTALL_FAILURE".

The label is wrong. A code saying installation failure stands in for one that should have said out of space.

The documented remedy is to enlarge that partition to 750 MB. Microsoft's KB5028997 carries the manual instructions.

Before you run that partition script

Now the part most pages leave out. It changes whether you should do this at all.

Reported by an owner, 20 June 2024, in a thread whose title is the whole warning: an invalid partition table error on boot after applying the script to fix KB5034441.

In his words: "Initially I did have the (0x80070643) error. I ran the script mentioned in the link above… After the script ran, I rebooted and got an Invalid Partition Table error. The PC cannot boot."

Microsoft's support representative acknowledged the underlying issue as a known one and walked him through reaching the recovery environment by forcing three failed restarts. The thread never records whether he got his machine back.

And the documented fix does not fit every layout. KB5028997 works when your recovery partition sits immediately after the Windows partition. Where it sits before the EFI partition instead, those instructions do not apply.

A second owner, May 2024, had a 530 MB recovery partition showing 100% free and still got the same error every time.

The answer he got is worth carrying. Disk Management does not report free space inside that partition accurately. It shows EFI as 100% free too.

⭐ Ours, and marked as ours: this update is optional in practice. KB5034441 patches the recovery environment rather than Windows itself.

For most home machines, leave it failing. Running diskpart against your own boot layout is the bigger risk.

If you do go ahead, image the drive first. Not a file backup. A full image, on something you can boot from. If space is what you are short of generally, finding the big items on a full drive is a safer place to start.

The component store family, which share one fix

Four codes, one cause and one set of commands. If yours is any of these, you can stop hunting.

0x80073701 is ERROR_SXS_ASSEMBLY_MISSING, which Microsoft describes as "The referenced assembly couldn't be found."

0x800f0831 is CBS_E_STORE_CORRUPTION, described simply as "Corruption in the Windows Component Store."

0x800f081f is a missing source for a package or file, and 0x80070570 is ERROR_FILE_CORRUPT.

Microsoft gives you the same mitigation for all four in its common update errors table, and names the cause as "component store corruption that was caused by a component in a partially installed state".

Open Command Prompt as administrator and run both, in this order:

Dism.exe /Online /Cleanup-Image /Restorehealth
Sfc.exe /Scannow

Then restart. Documented by Microsoft for every code in this family.

⚠️ The DISM line can sit at 20% for a long while. That is normal and it is not frozen. Leave it.

The codes that are not your computer's fault

Several of the most common ones are network or server problems. Repairing your Windows install will not touch them.

0x80072EFD, 0x80072EFE and 0x80D02002 are timeouts. Microsoft's mitigation is to make sure "no firewall rules or proxies block Microsoft download URLs".

0x80244022 is HTTP 503, which Microsoft describes as the service being "temporarily overloaded". That one is worth you simply retrying tomorrow.

0x8024401B is a proxy authentication failure, and 0x80072EE2 is the update agent being unable to reach the servers at all.

0x80072F8F is a decoding failure that Microsoft attributes to TLS 1.2 not being configured correctly on the client.

⭐ If your code is in this group, look at your network before your PC. A corporate proxy, a school filter, a VPN or an over-eager security suite produces all of them.

Ours, and marked as ours: disconnect the VPN, switch to a different network for ten minutes, and try again. That one test resolves more of this family than any command does.

0xc1900101, which means a driver

This one behaves differently from all the others. Knowing that saves a lot of pointless repair work.

Documented by Microsoft: "A result code of 0xC1900101 is generic and indicates that a rollback occurred. In most cases, the cause is a driver compatibility issue."

So the update did not fail to install. It installed, something went wrong, and Windows put your old version back. That is the system protecting you rather than breaking.

The answer is drivers. Specifically the ones Windows Update does not manage. Graphics, storage controllers, and anything you added to the machine yourself.

Microsoft's advice is to take third-party drivers "on the manufacturer's website" rather than trusting the automatic search.

Ours, and marked as ours: unplug everything you do not need before the retry. External drives, docks, printers, capture cards and USB hubs. A rollback caused by a device that was not attached cannot happen.

0x80070422, the thirty second one

Worth checking early. It is trivial and it looks alarming.

ERROR_SERVICE_DISABLED. Microsoft's description: "This issue occurs when the Windows Update service stops working or isn't running."

Open `services.msc` from the Run box, find Windows Update, and check it is running rather than disabled.

Did somebody once follow a guide about stopping Windows updates here? Then that is your answer.

0x800f0922 and 0x80070BC9, which are about policy and permissions

Two codes that mean somebody or something has changed how Windows is allowed to service itself.

0x800f0922 is CBS_E_INSTALLERS_FAILED. Microsoft's own note on it involves write permissions on the `C:\Windows\System32\spp\` folder for the User and Network Service accounts.

0x80070BC9 is ERROR_FAIL_REBOOT_REQUIRED, and Microsoft's explanation is worth quoting because it names a specific culprit: the TrustedInstaller service startup type being "set to Manual by a Group Policy Object".

Its note continues that the service switches itself from Manual to Automatic when an update needs a restart to finish, and that if the value is put back to Manual before the restart, "the transaction can't be applied".

⚠️ Both of these are common on work machines and rare on home ones. If yours is managed by an employer, this is the point to hand it to whoever manages it.

0x80070005 and the log that actually names the file

Access denied. It is one of the few codes where Microsoft tells you to read the evidence yourself.

Its instruction is precise. Go to `%Windir%\logs\CBS`, open the newest `CBS.log`, search for `, error`, and match the timestamp to when your update failed.

Scroll up from there and you will usually see which file or registry key was refused. That names the object whose permissions need changing.

⭐ This is the most useful habit on the whole page, and it works far beyond this one code. The CBS log is where update failures actually get written down.

When the code changes every time

Then you probably have two faults, or a failing drive. Chasing individual codes will not converge.

Run `chkdsk /f` and let it schedule for the next restart. Then run the DISM and SFC pair from the component store section. If the update is not failing but simply sitting there, a stuck update is usually not stuck is the page you want.

Ours, and marked as ours. Codes that keep moving after that are not an update problem at all. A drive that is failing to read consistently produces a different error on every attempt, and no update command addresses it.

Status: put together on 22 August 2026. Every code meaning and mitigation quoted above is taken from the Common Windows Update errors table, revised on Microsoft's own site in May 2026. That table does not list 0x80070643 at all, which is why this page treats it separately.

What does error 0x80070643 actually mean?

Officially ERROR_INSTALL_FAILURE, but on Windows Update it usually means the recovery partition is too small to stage the update. Microsoft states the wrong code is returned because of a fault in its error handling routine, standing in for an out-of-space message.

Should I resize my recovery partition to fix KB5034441?

Consider not doing it. The update patches the recovery environment rather than Windows itself, one owner's machine would not boot after running the script, and the documented instructions only apply when the recovery partition sits immediately after the Windows partition. Image the drive first if you go ahead.

Which Windows Update errors mean component corruption?

0x80073701, 0x800f0831, 0x800f081f and 0x80070570 all point at the component store. Microsoft gives one mitigation for the whole family: Dism.exe /Online /Cleanup-Image /Restorehealth followed by Sfc.exe /Scannow, then a restart.

Why does my update install and then undo itself?

That is error 0xc1900101, which Microsoft describes as a generic rollback, usually caused by an incompatible driver. Update graphics and storage drivers from the maker's site, and unplug every non-essential device before you retry.

The Short Version

• The code is the diagnosis. Find yours before running anything general.
• 0x80070643 is not an install failure. It is a full recovery partition wearing the wrong label.
• One owner's PC would not boot after running Microsoft's partition fix, and KB5034441 is optional.
• 0x80073701, 0x800f0831, 0x800f081f and 0x80070570 all take the same DISM and SFC pair.
• 0xc1900101 is a rollback, which means a driver, which means unplug things and retry.
• Timeouts, 503s and proxy codes are network faults. Change network before changing Windows.
• CBS.log in %Windir%\logs\CBS names the exact file that was refused.

Where to Next

Copy your code into a note before you close this page, then match it to the section above. Retrying a failed update without knowing which family it belongs to is how people lose whole afternoons.

If the update is not failing but sitting still, a stuck Windows update is usually not stuck and is a different page entirely. If the failures started alongside disk warnings, finding the big items on a full drive covers the space side.

If your code is not on this page, put it in a comment with the KB number beside it. I add them as they come in, and the odd ones are the ones nobody has written up.