For many months now, a certain Windows bug has been causing update installation problems for some users.

When trying to install update KB5034441 for Windows 11 or KB5034440 for Windows 10, you might experience an installation failure that cancels the entire process with error code 0x80070643 or 0x80070643 - ERROR_INSTALL_FAILURE.

Since these patches are meant to address security vulnerabilities, it’s important to install them as soon as possible. But what do you when you can’t? What’s causing this issue?

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The problem stems from the fact that your Windows recovery partition isn’t large enough to complete the update. This would cause the update to WinRE (Windows Recovery Environment) to fail.

Microsoft has yet to solve the issue, but they’ve at least provided some self-help instructions. These instructions aren’t exactly easy to implement, though, and they require a certain level of technical understanding.

Here’s what you do: First, check whether your WinRE version is up-to-date, then check whether your Windows recovery partition is large enough (i.e., at least 250 MB). If the recovery partition is too small, you can adjust the size accordingly. If WinRE is already up to date or no WinRE partition exists at all, this error message will not appear when installing the updates in question.

Microsoft explains exactly how to solve the 0x80070643 problem for Windows 10 and Windows 11 and, if necessary, how to adjust the size of the recovery partition in these documents:

For KB5034440 and Windows 11For KB5034441 and Windows 10

This article originally appeared on our sister publication PC-WELT and was translated and localized from German.

Author: Hans-Christian Dirscherl, Managing Editor, PC-WELT

Hans-Christian Dirscherl began his IT life with Autoexec.bat and config.sys, Turbo-Pascal and C, Sinix and Wordperfect. He has been writing on almost all IT topics for around 25 years, covering everything from news to reviews and buying guides.

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