Here is a small guide (only for Win 10) that helped me. (It may not help everyone).

All changes are at your own risk.

Important !!! – First close all programs –

  1. Enter “Environment variables” in the search bar at the bottom left and start

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  1. Click on environment variables

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  1. Im unteren Bereich (Systemvariablen) auf “Neu” klicken

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  1. First assign a name and then click on “Search file”.

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  1. Navigate to your RoM installation directory and search for the file “Client.exe.ini” !!! Important. This is not the application file but the configuration file !!!

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  1. It should then look like this

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  1. Confirm all windows with “Ok” and then shut down and restart the computer (please do not perform a quick start)

Now the error should no longer occur. In any case, it has already helped several people.