ubuntu encountered the following problem installing the graphics card driver
ERROR: The kernel module failed to load, because it was not signed by a key that is trusted by the kernel. Please try installing the driver again.
and sign the kernel when prompted to do so.
ERROR:  Unable to load the kernel module ‘nvidia.ko’. This happens most
frequently when this kernel module was built against the wrong or
improperly configured kernel sources, with a version of gcc that
differs from the one used to build the target kernel(1), or if a driver
such as rivafb, nvidiafb. or nouveau is present and prevents the
NVIDIA kernel module from obtaining ownership of the NVIDIA
graphics device(s), or no NVIDIA GPU installed in this system is
supported by this NVIDIA Linux graphics driver release.

Solution:
Enter BIOS to turn off Secure Boot

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