Windows, how to clean up unused COM ports

by luca
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It certainly happened to you that, when you connect a new USB device to your Windows PC, the operating system assigns the device a COM port with a high number because of the previous ones are in use:


Windows indeed keeps the COM port reserved even if the device is not physically connected to the computer. You can clear some old reservations with the following steps:

– run a command prompt as administrator:


– type the following commands:

set devmgr_show_nonpresent_devices=1
start devmgmt.msc


– choose View – Show hidden devices:


– you can now remove (uninstall) old devices and free the associated COM ports:


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