When I run software updater it says that it failed to download repository information and to check Internet connectivity.
I have Internet connectivity.
How do I fix this?
editing to add content of sources,list:
sorry I can't figure out how to paste in the content of sources.list without making a huge mess. Some of it previews as really large bold print. I tried to follow the block quoting and code rules but it is a huge mess anyway.
Another solution is, sometimes it couldn't find the packages from the selected server. You should change it to the best matched server.
OtherSelect Best Server and it will auto update the sources.sudo apt-get upgrade
In my experience, there are at least three other causes of the failure: incorrect repository location, repository is down, and incorrect proxy settings.
First, check your software repository location in /etc/apt/sources.list or run software-properties-gtk. Make sure you can reach all of the repository, e.g. by using the web browser to make sure that the site is not currently down.
If it's OK, then check your system-wide proxy settings. Because software update is run by using root privilege, so the proxy settings used would be the root's too. Check this question to set system-wide proxy settings.
Another cause might be firewall, but I'm not sure :).
Hope it helps.
UPDATE
It is not a problem if you get message gpg: /tmp/tmp<somerandom>/trustdb.gpg: trustdb created when running software-properties-gtk from the terminal.
In my case the error messages about not being about to get repository information, checking internet connectivity and not being able to find a "Best Server" were complete red herrings.
The root cause of my problem was that I was trying to upgrade from 13.10 to 14.04 and my update settings were set to only check for LTS updates. Whenever I tried explicitly checking for an update, it said "your system is already up-to-date". I wrongly guessed at first that this was due to a network issue (proxy etc) leading to no updates being found.
When I changed the updater settings to check for ANY new version, I got a message saying 13.10 is no longer supported, with a new button for the upgrade option. Clicking this new button worked fine, with no other network or settings changes.
This looks like a bug to me, since 14.04 is an LTS update, but anyway, it worked!
In my case, the error messages start showing after upgrade to ubuntu 20.04. When I changed network proxy settings from Automatic to Disabled error disappeared.
Here is how:
Run sudo apt update in terminal and check what error it says run software-properties-gtk and go to other software and uncheck all the error causing ones and then run sudo apt update it will work
Try sudo ldconfig /usr/bin/gpg. See: https://unix.stackexchange.com/a/677711/114401
It worked for me. sudo apt update now works again.
