Hello,

it is a daedalus installation with the 470-nvidia-driver (470.129.06-6).
The driver finally seems to work, but the "nvidia-persistanced" error remained.

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edit / update: replicated installation, error and fix

Problem: apt does not 'fully install' nvidia-persistanced.
But: It will succeed, if nvidia-persistanced is not running.

$ /etc/init.d/nvidia-persistenced stop
$ apt-get upgrade  

And apt should be happy again.

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I leave the original post below, since it was posted and happend so on my box.
By now, I think I must have stoped the daemaon sometimes and forget about it.
end edit / update
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The following solved it in my case:

$ sudo rm /var/run/nvidia-persistenced/nvidia-persistenced.pid
$ sudo rm /var/run/nvidia-persistenced/socket
fixed it and
$ sudo apt-get upgrade

then succeeded in finalising the post-install-script and starting nvidia-persistanced.
Done.

Some remarks:
Probably, it is a good idea to gzip or move both files instead of deleting them.
It took some time to notice that it is just a daemon, that did not start.

$ /etc/init.d/nvidia-persistanced start

gave an error message respective a pid-file. Messing around with it may or may not result in other hints, if the above does not work.
apt insists to start the daemon by itself, so if you managed to start the daemon, you have to stop it before doing "apt-get upgrade".

Hope this is helpful.
Regards