KB5034441 is a security update for the Windows Recovery Environment (WinRE) to fix a vulnerability that could allow bypassing BitLocker encryption. However, some users have reported that the update fails to install with an error code 0x80070643.
Microsoft has confirmed that they will not automatically fix this issue in a future update. The underlying issue is that the WinRE partition does not have enough free space for the update, requiring a manual resize of the partition to make room for the update.
To fix this issue, Microsoft has provided a couple of solutions: manual Command Prompt instructions or a script that can be run to increase the size of the WinRE partition by an additional 250 MB. This can be done by shrinking the system partition by the same amount.
It's worth noting that KB5042320, which replaces KB5034441, also fails to install with the same error code for some users. The underlying root cause for failure is still not fixed, and users are advised to hide the update or set the "WinREVersion" registry entry to at least "10.0.19041.3920" to prevent the update from being offered.
