Virtualbox and Serial Port permissions for Windows10


I am using Windows10[HostOS]. I wanna create a virtual environment(windows7[GuestOS]) on Oracle VirtualBox(Ver5.2.18 r124319). However, I get the following error.

How can I check this permission?

[MyPC Settings]
 HostOS Serial port  :COM3
 GuestOS Serial port :COM1

[VirtualBox Error]
 Cannot open host device 'COM3' for read/write access. Check the permissions of that device (VERR_ACCESS_DENIED).
 Exit Code : E_FAIL (0x80004005)
 Component: ConsoleWrap
 InterFace: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}
asked on Super User Jul 23, 2019 by T.Endo • edited Jul 23, 2019 by harrymc

1 Answer


The port might be in use on the host. Here is how to find out.

  • Download and install WinObj
  • run WinObj and click on the left the entry named GLOBAL??
  • Search for COM3 on the right. The SymLink column will display a device name, perhaps \Device\Serial2.
  • Download and install Process Explorer
  • Run Process Explorer and open the search dialog via Ctrl+F and type the serial device name (e.g. \Device\Serial2) and press "Search".
  • The process that is owning the file should be selected.

If that doesn't help, please include a screenshot of the mapping in Virtualbox of COM3 to the VM's COM1.

answered on Super User Jul 23, 2019 by harrymc

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