msiexec /unregister msiexec /regserver net stop msiserver net start msiserver

Follow these sequential troubleshooting procedures to clear out driver blockages and complete your installation. 1. Completely Purge Leftover Kaspersky Traces

Once the installation succeeds, return to msconfig and re-enable your services. To help you faster, let me know: Which are you using? Did you have a different antivirus installed previously? Are you trying to upgrade or perform a fresh install ?

Why this works: kavremover deletes klif.sys and its registry entries even if Windows denies access during normal uninstallation.

Insufficient permissions block driver writes.

The klif.sys-x64 driver is part of the core security framework that Kaspersky uses to protect against rootkits and network threats. When this driver fails to install (Error 27300), it's generally due to: