Cannot install update on Plesk for Windows: The installation of the package 'plesk-modsecurity-module' failed with code 1603

Symptoms Plesk update installation fails: PLESK_ERROR: Error: The installation of the package 'plesk-modsecurity-module' failed with code 1603. (upgrade: Upgrading ModSecurity IIS Module...) Cause Windows msiexec failed to update ModSecurity IIS module. Code 1603 is generic error, and issue could be caused by various reasons (which might be logged in Plesk autoinstaller3.log file). Resolution Reinstall ModSecurity from scratch after installing Plesk update. Reinstall ModSecurity: Connect to the server via RDP Open cmd.exe and remove ModSecurity modules from IIS: C:\> %windir%\system32\inetsrv\appcmd.exe uninstall module "ModSecurity IIS (32bits)" Uninstalled MODULE "ModSecurity IIS (32bits)" C:\> %windir%\system32\inetsrv\appcmd.exe uninstall module "ModSecurity IIS (64bits)" Uninstalled MODULE "ModSecurity IIS (64bits)" Restart IIS: C:\> iisreset Remove ModSecurity component from Plesk: C:\> plesk installer --select-release-current --remove-component modsecurity Install Plesk update: C:\> plesk installer update Install ModSecurity component: C:\> plesk installer --select-release-current --install-component modsecurity