I had the same problem when I installed the rpa desktop for the first time.
This error is shown when the communications between the rpa processes fail. In other words, when the processes are not able to communicate with the rpa server, that message appears.
To fix it, you have to reinstall rpa desktop, but be sure that you have disabled the antivirus before starting the installation. Once you have reinstalled the rpa desktop, it is mandatory to add an exclussion to Windows Defender. Just include the folder where the rpa desktop was installed to the exclussion list.
I hope this may help you.