How can I get updates or install new packages for Ubuntu 17.04?
Right now when I run apt-get update or try to install new packages I'm getting a 404 not found, or a similar error. How can I work around this?
Ubuntu 17.04 has reached it's end-of-life, so it's no longer being officially supported. This means that official repositories and mirrors won't have any packages or updates available.
However, there may be third party repositories you can use instead. You'll have to add the software repositories manually in order to use them. I've not used it personally but ubuntuupdates.org looks like a good resource to find third party repositories and package updates.