ERRORMSG: Error occurred opening comms, Access is denied

Article ID: 060927sab
Last Reviewed: July 10, 2023

The information in this article applies to:


Pronto for Windows produces the error message when starting Download or opening the Control Panel.

Error occurred opening comms: Access is denied.


This is usually due to the specified serial port being in use by another process running on the machine.


Check each running process to ensure that the port has not be opened by it. Bear in mind that a process may be running in the background or on a Windows machine running under a another logged in user.
The following application is known to frequently cause this problem.

Microsoft ActiveSync.

This runs in the background when a PDA or Mobile phone is not connected.
To check if it has reserved the port:
1) Double click on its icon in the tool tray area of the Taskbar, and active sync will open.
2) From the FILE menu select the item CONNECTION SETTINGS.
3) On the Connection settings dialog, if the Allow connections to one of the following checkbox is set, check which port is listed.

Other applications:

Known or suspected of running in the background and reserving the port for themselves.

Fax or modem software.