MICROSOFT APRIL UPDATES BREAK THIRD-PARTY BACKUPS

Microsoft acknowledged the problem after reports surfaced that its latest security patches introduced compatibility issues with third-party backup software. The failures stem from changes to the psmounterex.sys driver, a Windows component used by numerous backup applications to access system files and volumes. Users running affected backup tools have experienced complete backup failures or data access errors since applying the April updates. The impact spans multiple backup vendors, indicating a widespread compatibility problem rather than an isolated incident. Microsoft's support team confirmed the connection between the April patches and the backup failures. The company has not yet released a fix but stated it is actively investigating the driver changes that triggered the incompatibility. Users currently affected have limited options. Some have reverted to previous Windows versions, while others have disabled automatic updates pending a resolution. Backup vendors are also working to update their software to accommodate Microsoft's driver changes. The incident highlights ongoing tensions between Windows security updates and third-party software compatibility. Microsoft prioritizes security patches on its monthly update cycle, but changes sometimes conflict with applications that interface directly with system drivers. Microsoft has not provided a timeline for resolution. The company typically issues patches on the second Tuesday of each month, suggesting a fix could arrive in May if prioritized. Until then, organizations relying on affected backup solutions face operational disruptions. Administrators should check their backup vendor's website for any interim workarounds or compatibility statements. Microsoft recommends contacting affected vendors for guidance on whether reverting updates is advisable for their specific environments.