This is caused by running an out of date simulator.
Players run into this problem because they make the incorrect assumption that the launcher is just an installer and then make a shortcut to the main VelociDrone program in order to run it.
This is incorrect and leads to problems. Do not make a shortcut to the main VelociDrone program, if you are going to make a shortcut make it a shortcut of the launcher.
Running the launcher ensures that your simulator stays up-to-date with fixes and new features and that you run bug free.
If you do not update your simulator when we release updates then you can suffer multiple problems ...
inability to see multiplayer sessions
inability to load new tracks
hangs or crashes running the simulator
missing announced functionality
The fix to the "invalid request received" issue is just to run your launcher and update the simulator.
Ensure you delete any shortcuts you made to the simulator and always in future start the simulator via the launcher.
If you don't have the launcher anymore then it can be downloaded from our website downloads page.