Problem: Ubuntu 18.04 installs the graphics card driver normally. When the Ubuntu system is opened, the graphics card driver cannot be used. Use NVIDIA SMI to check the above errors.

resolvent:

Just execute two commands:

Sudo apt get install DKMS
sudo DKMS install – M NVIDIA – V 440.44 (440.44 indicates the driver version number)

Use the command ll/usr/SRC/to view the nvidia-440.44/ folder below. The version number varies from computer to computer

Then restart the computer, success.