By following the steps above, you should have your Canon MF printer/scanner installed and fully functional in no time.
This method only works if the port monitor DLL ( CNMNPU.DLL or similar) is already present in C:\Windows\System32\ . If not, you must first extract the driver package and manually register it using regsvr32 . could not install canon mf port monitor exclusive
Some security software quarantines or blocks printer port monitors because they modify network or port settings. This is especially true for third-party antivirus suites like McAfee, Norton, or even Windows Defender’s “Controlled Folder Access.” Troubleshooting Guide: "Could Not Install Canon MF Port
If a clean uninstall is not possible or fails, the user must manually . By navigating to the Windows Services application (services.msc), the user can locate "Print Spooler," stop the service entirely, and then restart it. This action releases any locked files the service was holding. In severe cases, the user may need to navigate to the C:\Windows\System32\spool\drivers folder to manually clear out the print queue and driver cache before restarting the service. Press Shift while clicking Restart (from the Start menu)
Shift while clicking Restart (from the Start menu).7 or F7 to select "Disable driver signature enforcement."