Ubuntu 20.04 update problem ("404 Not Found [IP: ]" error) [duplicate]

Solution 1:

Yes, you can remove the CD-ROM (or or original installation media) from the sources.list

Edit the sources.list file with the following command:

sudo nano /etc/apt/sources.list

And near the top, comment out the line that looks like this:

deb cdrom:[Ubuntu-Server 9.04 _Jaunty Jackalope_ - Release i386 (20090421.1)]/ jaunty main restricted

(comment is a hash (#) - so pop one of these at the start of the deb cdrom: ... line)

Press Ctrl+X to exit the nano text editor, pressing y to save your changes

Then finally you'll need to run:

sudo apt-get update

To update your package lists.

Solution 2:

For 12.04 and 12.10

This feature i.e auto enabling of the installation medium as software sources is disabled in this release. The section is empty now by default and will say this:

To install from CD-ROM or DVD, insert the medium into the drive

Here is a screenshot added

I think, this will be continued in the coming releases also.