If you have received this message the cause is almost always a result of multiple instances being open, this is most likely to occur the very first time you run the program after installation.

To resolve this either

A: Right click on the GG system tray icon and click exit, then open task manager and manually end all GameGlass processes.

B: Simply restart your PC to accomplish the same thing

You should now be able to launch the GameGlass Host software without encountering this error again.