Can't update to 8.17.2 in Pi 4b

Can’t update to 8.17.2. Please check the screenshot attached:

Could you post the contents of /etc/apt/sources.list resp. the contents of the files within /etc/apt/sources.list.d/?
Strange, that there is a Debian stretch entry.

I guess he has setup Unify software with a 3rd party script of Glenn? Err:8 stretch Release │ │ 404 Not Found [IP: 80] - #13 by srdempster

Yes I have an unifi controller running on this device. What should I do?

Edit: but I never had issues with it before.

You need to remove the 3rd party source file configuration. Simply you have something configured pointing to Debian Stretch apt package source. However Stretch is being removed globaly on Debian package server and moved to the archive folders.

The issue is not related to DietPi. It’s because of the way how Glenn setup this Unify stuff. Maybe someone would need to contact him asking if running a newer version of his script would update the old source file configuration.

glennr-install-script.list  plexmediaserver.list
mongodb-org-3.6.list	    plexmediaserver.list.dpkg-dist
mongodb-org-4.4.list	    raspi.list
nodesource.list		    sonarr.list

These are the sources that I have. Should I delete the glennr one? Is it safe?

edit: it did the trick