April KB5083769 Windows 11 update causes backup software failures
Summary
Microsoft's April 2026 KB5083769 security update for Windows 11 has caused failures in third-party backup software on specific versions of the operating system. Users are reporting that backup applications from various vendors are no longer functioning correctly after the update, potentially leading to data loss risks.
IFF Assessment
This update negatively impacts critical data protection mechanisms, posing a risk of data loss for users and organizations.
Defender Context
This incident highlights the potential for even routine security updates to inadvertently disrupt essential security functions like data backups. Defenders should carefully test Windows updates in controlled environments before widespread deployment and have rollback plans in place, especially for critical systems.