Im using VRay for Modo v 3.60.01 and all was well until I could not do a GPU render and got a licence server error. I updated just now to LS 5.2.0 and even following a reboot, I still get the attached error message.
Please could you advise, as I need to get up and running again asap.
I had the same problem. I lost more than an hour of work trying to fix it, in the end going to the license server page (http://localhost:30304/#/) and deactivating and then reactivating fixed it.