Microsoft confirms April Windows updates cause backup failures

BleepingComputer

May 4, 2026 at 10:40 AM

Overview

Microsoft has acknowledged that the April 2026 security updates for Windows are causing issues with third-party backup applications that rely on the psmounterex.sys driver. This problem is affecting various backup solutions, preventing users from successfully backing up their data. The situation is significant as it could lead to data loss for individuals and businesses that depend on these backup tools for data protection. Microsoft has not yet released a specific fix or workaround for this issue, leaving users in a precarious position. Companies and users are advised to monitor for updates from Microsoft regarding this ongoing issue.

Key Takeaways

Affected Systems: Third-party backup applications using psmounterex.sys driver
Timeline: Disclosed on April 2026

Original Article Summary

Microsoft has confirmed that the April 2026 security updates are causing failures in third-party backup applications using the psmounterex.sys driver. [...]

Impact

Third-party backup applications using psmounterex.sys driver

Exploitation Status

No active exploitation has been reported at this time. However, organizations should still apply patches promptly as proof-of-concept code may exist.

Timeline

Disclosed on April 2026

Remediation

Not specified

Additional Information

This threat intelligence is aggregated from trusted cybersecurity sources. For the most up-to-date information, technical details, and official vendor guidance, please refer to the original article linked below.

Related Topics: This incident relates to Windows, Microsoft.

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