With the nVidia graphics cards, in a Mac Pro (for those of us who refuse to let go) or PCIe Thunderbolt brethren, you probably by now are used to updating the drivers with every OS X version. However, sometimes when trying to update the nVidia drivers will give an installation failed after appearing initially to install correctly, ending with generic a "contact manufacturer" error. This error isn't exactly telling the full story, OS X post 10.10 has feature called System Integrity Protection, which protects certain system files from being modified by even the root user, which stops malicious installers/rootkits from tampering with macOS. This error also can adversely sometimes affect no longer used files such as items placed in the "incompatible items" folder, and when the user tries to delete them, will receive a "can't be modified or deleted because it's required by macOS" error message.
It's very important to understand that you should only do this with installers from a valid source before proceeding, such as directly downloading drivers from nVidia and using its certificate check or to remove offending drivers or files. After performing necessary changes, re-enable System Integrity Protection.
First to make sure you have System Integrity Protection, go to the terminal and run
This should return a status of enabled.
Restart your Mac, and hold down Command-R keys during startup. This should boot your computer into recovery mode (alternately, you may be able to hold option and select the recovery partition). This may take a few minutes to boot.
Ignore the installer prompt and select from the Utility, Terminal and run:
Reboot. Perform the necessary change boot back into recovery mode as before.
Reboot. You can now check using the
csrutil status to see if the csrutil is working.