Microsoft's latest update, KB5074109, is causing boot failures in Windows 11 systems, resulting in a stop code error UNMOUNTABLE_BOOT_VOLUME (0xED). This error has surfaced primarily in versions 25H2 and 24H2 of Windows 11 after the mandatory security update was applied.
Effect on Windows Systems
KB5074109, released in January, was aimed at patching various security vulnerabilities. However, the unintended consequence is a failure to boot, which manifests as a black screen error. Microsoft has acknowledged receiving several reports of this issue and is urging affected users and administrators to contact them with detailed information.
The black screen error is typically linked with system corruption or hardware issues, but in this case, seems to be affecting software configurations. While Windows Recovery Environment (WinRE) often resolves the problem, some cases require a full system reinstallation via ISO files.
Initial Response and Recommendations
Microsoft has not yet quantified the number of affected users but stresses the importance of user reports to assess the extent of the problem. This update follows other recent patches addressing shutdown failures and remote login difficulties earlier in January.
- KB5074109 is causing boot failures in some Windows 11 systems.
- Error code UNMOUNTABLE_BOOT_VOLUME (0xED) is displayed during boot.
- Windows 11 versions 25H2 and 24H2 are primarily affected.
- WinRE may resolve these boot issues, though clean installs are sometimes needed.
- Microsoft is seeking user reports to gauge impact.
For affected users, it is recommended to report the issue to Microsoft to aid in identifying a comprehensive solution. Meanwhile, some relief can be found using WinRE or performing a clean installation if necessary.
