code integrity enforcement

Code integrity enforcement on Windows refers to the security mechanism that validates kernel-mode drivers and system files before they are loaded. Microsoft uses this feature to block vulnerable or malicious drivers, as seen in the April 2026 update KB5083769, which deliberately blocked the psmounterex.sys driver due to security concerns. This action caused backup image mount failures in some third-party tools on Windows 11, Windows 10, and Windows Server. The recommended fix is updating the affected backup application rather than rolling back the Windows update. Code integrity enforcement thus balances platform security with potential compatibility impacts on enterprise and consumer systems.