Sophos Endpoint Security and Control: 'Could not copy RMS config file cac.pem' error after third-party security software is removed

Issue
After using the 'Protect computers wizard' in Sophos Enterprise Console, version 3.1 and above, with 'Remove third-party security products' selected, the third-party security software is removed, but the error 'Could not copy RMS config file cac.pem' is displayed in Enterprise Console. The Sophos software is not installed.

Sophos product and version
Sophos Endpoint Security and Control, version 8.0 and above
Sophos Enterprise Console, version 3.1 and above

Operating System
Windows 2000+

What to do

This issue occurs when the third-party software has been successfully removed, but its driver is still running.

To resolve the problem, reboot the affected computer. When the computer has rebooted, click 'Protect computers' again to install the Sophos software.