Real-time protection from Windows Defender, McAfee, Norton, or others can block the port monitor.
Some security software may mistake the Canon driver installation for malicious activity, locking the files required for the port monitor. Temporarily disable your antivirus or firewall. Run the driver installer. Re-enable your security software immediately afterward. How to Prevent Future Installation Issues could not install canon mf port monitor exclusive
If you’ve recently tried to install a Canon multi-function (MF) laser printer or scanner on a Windows computer, you may have encountered a frustrating roadblock: a setup failure accompanied by the error message: Real-time protection from Windows Defender