Sometimes you come across an error which reads “The specified port is unknown” when you are doing the installation of a new hardware like printers. It will come up when the installer requests to connect the USB cable to the computer. It will make you quit the installation shortly after with the specified port is unknown error message. Here I took up HP printer and let us see how to come over this problem.
The port will be a USB port and a quick check revealed that there was not a USB0001 port which usually is created when adding a USB printer to the computer system. The printer worked fine on another computer system running Windows Vista Home Premium which confirmed that the printer was working fine and the problem to be located on the first computer system running Windows XP.
In order to fix this error, The first thing that had to be done was to uninstall all leftovers from the installation of the HP printer. This can be done with the HP Scrubber software which should be available on the installation CD. The uninstallation software can also be downloaded directly from the HP website. (It is located in the /ccc/ folder on the disk and can be started by clicking on uninstall.bat)
All leftovers were removed after a reboot which ensured that the next installation would be a clean one. The problem hat to be connected to the USB Monitor. A quick look in the Windows Registry verified that assumption.
Start the Windows Registry Editor with [Windows R], [regedit] and [enter]. Now navigate to the following Registry key:
HKEY_LOCAL_MACHINE/System/CurrentControlSet/Control/Print/Monitors
Check if a subkey with the name USB Monitor exists. If not create it by right-clicking Monitors and selecting New > Key. Name that key USB Monitor.
Now right-click in the right pane and select New > String Value from the menu. Enter Driver as the name. Double-click driver and enter usbmon.dll as the value.
Now restart your computer and perform the printer installation again. The installation should go through without problems now and the error message the specified port is unknown should not appear.
This also worked perfectly on an Epsom Start TSP100 EPoS printer. Wonderful work, thank you.
solution worked perfect. Thank you very much.
That relieved my headache.
Thank you!!!