I'm using Debian Stretch 64-bit with Gnome 3.22.2. When trying to update the NVIDIA driver, I got the following message:
ERROR: An NVIDIA kernel module 'nvidia-drm' appears to already be loaded in your kernel. This may be because it is in use (for example, by an X server, a CUDA program, or the NVIDIA Persistence Daemon), but this may also happen if your kernel was configured without support for module unloading. Please be sure to exit any programs that may be using the GPU(s) before attempting to upgrade your driver. If no GPU-based programs are running, you know that your kernel supports module unloading, and you still receive this message, then an error may have occured that has corrupted an NVIDIA kernel module's usage count, for which the simplest remedy is to reboot your computer.
How do I know if my kernel supports module unloading?
I'm trying the other solutions too, but no success up to now.