I thought i would post this fix has it helped me and may help others. I came across when trying to update my pi-star, namely :
E: The repository ‘http://httpredir.debian.org/debian bullseye-backports Release’ no longer has a Release file.
It was giving me a headache.
To fix this you simply login to your pi-star via ssh using pi-star has the username and raspberry has the password.
Once logged in you need to edit the bullseye-backports.list
Enter the below command:
sudo nano /etc/apt/sources.list.d/bullseye-backports.list
Once opened in nano editor simply swap the domain to http://archive.debian.org/debian
Then hit ctrl and x to exit then y to save.
