Linux Lite 5.2 Release does not have a release file

[Moltke]

Because the system is running off the installation media you can't update - that mode is meant just to try out the software to make sure it runs on your hardware and if all ok it allows you to go ahead to install onto hard disk.

Not entirely true, you can update sources and even upgrade the system while in live mode, I've done it, however, if there are too many updates, it won't work since there would be no enough space.

[member=42456]wildflower86[/member] can you show us your sources file? It's in /etc/apt/sources.list.d just copy/paste its contents here.