That’s false. CUDA drivers are backwards compatible, so we will just download an older version of CUDA.
Your issue is that your driver set-up is broken, error 999 gets thrown by the driver when something serious is wrong. CUDA.jl. doesn’t even get to the point of downloading or looking for the CUDA toolkit. So try rebooting, re-installing your driver (making sure your libcuda, which is part of the driver, matches the exact version of the NVIDIA driver), etc.