The influence of nvidia-smi error message

Following error message is appeared when I run nvidia-smi command.(Ubuntu 16.04 (4.13.0) / CUDA-9.1)

NVIDIA-SMI has failed because it couldn’t communicate with the NVIDIA driver.
Make sure that the latest NVIDIA driver is installed and running.

It seems driver does not works well.
Please kindly share the influence of this error message and driver instillation failure.

Your system may simply require a reboot.

Otherwise the driver install is broken. Follow the CUDA linux install guide instructions carefully.