Comment 25 for bug 1921536

This bug is about installing on a system with a different version of binutils. I assumed that is what you are doing because that is what this bug is about. But based on your comment @khteh, I now assume that you are not hitting the problem I reported. Do you have a reason to believe your issue is caused by binutils, or are you just seeing this same error message?

modprobe: ERROR: could not insert 'nvidia': Key was rejected by service

binutils version differences is not the only reason you might see that error. You may be having an issue unrelated to this bug.

One possibility is that the installation method you selected is trying to build its own version of the module, which is not signed by a trusted Canonical key. The fact that you have a make.log at all (as shown in comment #19) is a hint there. nvidia-driver-535 will try to install the prebuilt and signed modules where possible, but if it can't, it will revert to installing the "source" and building an unsigned one instead. If you have the nvidia-dkms-535 driver installed instead of linux-modules-nvidia-535-generic, then that may be what happened.

If that is the case, you can try switching to the prebuilt/signed one by running:

 sudo apt install nvidia-driver-535 linux-modules-nvidia-535-generic
 sudo apt remove nvidia-dkms-535
 # ^ That should only remove nvidia-dkms-535

I hope that fixes your system.