Several common things can cause update errors, and not all are related to user errors. Often users add PPAs without a release file. Occasionally a server/mirror goes offline or moves. Sometimes a user's disk is failing or full. Sometimes RAM fills and moves to swap with errors that require reboot to remove and/or install. More commonly with dpkg errors WIFI hardware errors during downloads corrupt the dpkg staus file with bad characters or missing package headers. Linux Lite has built in tools for fixing these things in Lite Tweaks. If you don't like simple fast free try the solutions below.
Generally you can run: sudo rm -rf /var/lib/apt/lists/*And then run: sudo apt-get updateThis will usually fix 404 errors. It will let you know if errors persist so you can take another course such as changing mirrors etc.
Running: sudo dpkg --configure -a will not necessarily fix anything. It will report errors in a dpkg status file, but usually will stop at the first one. I stopped using -f commands with updates as problems can get worse if indeed you have a corrupted dpkg status file. The other option is to edit the dpkg status file. Run: sudo nano /var/lib/dpkg/status and correct the file. If it has missing headers or terribly corrupted package files just delete that package section and save the file. If it's only character or unexpected line errors you can fix it yourself with a good guess if you're a good speller or familiar with how it should look. Run sudo dpkg --configure -a after each correction you make. If there are several to make it will progress down them through the file as you go giving their locations by line numbers.
I personally believe that WIFI connections are the number one cause of update errors with user added PPAs a close second. Solution: use an ethernet connection to update and don't add PPAs without knowing what you're doing.
TC
