A thorough solution to the problem of a COM port being occupied (in use)

1. How do I release a occupied COM port?
As a result of repeated testing of different versions of Bluetooth drive, resulting in COM5~COM15 are occupied, and finally successfully installed after the driver can only use COM16, synchronization software is not recognized, which master can explain? Thank you!
2. In the use of USB to the serial port device, because the previous device has a problem, after the new device found that the previous use of the COM port is now displayed in use, the device newly allocated COM port number is from the previous beginning, for example: previously tried to COM7, after the new equipment came out of the direct is COM8 , com2-com7 are displayed in use (COM1 is machine-retained)
3. How do I delete a COM port that I used in My computer?
My computer often uses Bluetooth, mobile phone data cable and other things, each time a new device, Windows automatically assigned a new virtual COM port, now plug in the new device is used to COM25, view Device Manager-Port-COM25 Properties-Port Settings-Advanced-com port number, Discover from 3~24 All is "in use", how can the front of these delete?


A complete solution to the above problems:

Open the registry hkey_local_machine\system\currentcontrolset\control\com Name Arbiter
Remove the Comdb and try again! (Note: This will rebuild all COM ports). If not, restart your computer!

Note: The above approach solves my problem ...

You can also see whether the integrated modem occupies your serial port.

Open the Phone/modem options in the Control Panel,
Is there a connection in the Modems tab that occupies this serial port (such as COM1)


Workaround:

If there is a connection to occupy this serial port, directly delete this connection, restart the computer, problem resolution.

or look at the detailed reasons:

1, using Safe mode to start, with the system's own communication in the "Super Terminal" Test serial port (COM1),
The same error, but the wrong information more detailed, as follows:

Error message ********

Windows reported a TAPI error (80000048).
Use the phone/modem options in the Control Panel
icon to confirm that the modem is installed correctly.

**********************

2, then the computer started normally.
Open the Phone/modem options in the Control Panel,
Discover that there is a connection in the Modems tab that occupies this serial port (COM1),
Then delete the connection immediately.
Then use "HyperTerminal" Test serial port (COM1), no error,
Indicates that the communication with the serial port (COM1) is normal.

3, the serial port device connected to the serial port (COM1), with the relevant software and equipment communication, normal, problem solving.

About COM port occupancy issues with Bluetooth devices

Due to Windows inexplicably registry reason, many users found that after the installation of Bluetooth management software, the corresponding Bluetooth virtual port actually become COM9, or even COM13 or higher, resulting with many applications, such as mobile phone synchronization software, PDA synchronization software can not be used, Reinstalling the Bluetooth management software multiple times will only make the situation worse.

The solution is as follows (be sure to uninstall the Bluetooth hypervisor and restart it before performing the following steps)

1. In Windows system, press Start > Execute > Input cmd, press ENTER
2. After the command Character window appears, enter
Set Devmgr_show_nonpresent_devices=1
Press ENTER
Devmgmt.msc
Press ENTER
3. Then click > View > Show hidden devices in Device Manager
You can now delete the redundant port, after the deletion, please be sure to restart the boot

4. Reinstall the Bluetooth management software

5. If you want to permanently put this environment variable into XP, after going to my Computer > Click to select it, right-click > Properties > Advanced > Environment variable
In the system variable, press "new", in the "variable name" filled in "devmgr_show_nonpresent_devices", the value of the variable to fill in "1
"

A thorough solution to the problem of a COM port being occupied (in use)