NO_PUBKEY 4EDE055B645F044F NO_PUBKEY 8DD48989F43719CA

[Şerban S.]

Hi!

I remember having the same trouble some years ago.
Unfortunately, server error messages are very confusing and often, unspecific or even worse, they are pointing to a false direction.
This is what you can do for now:

1. Go to "Software & Updates". Launch the App.
In this window, there are seven tabs.
In the first tab, you have the option to choose the server you want to use as source for your downloads.
In many cases, the server is too far from your location and the response time is too long. This usually generates random error messages, like the ones in your log file.
2. Click on the combo box beneath "Download from" label. The default setting is "Server for US".
You will be presented two choices: The current selected server (US) and "Other"
3. Select "Other". This will pop-up a new window.
4. Click  the button "Select best server". A message box will appear, stating "Testing download servers". You'll see a progress bar.
After the test completion, look for a selected server address.
In my case, the menu "România" is expanded (all others are collapsed) and the best server address is hilighted: "ubuntu.mirrors.linux.ro"
Something similar will be in your case, pointing to the nearest server. ("nearest" has nothing to do with the idea of geographical distance, it is about the signal routing, server farm power, etc.)
Often "nearest", might be a server that is miles away from your physical location.
After selecting the suggested server, you can finish this stage.
5. Open the Terminal and type:

Code:

sudo apt update

Do it twice, to be sure the server addresses and the software lists are updated.

6. The next step is:

Code:

sudo apt upgrade

If the problem still occurs, it is above my current knowledge and understanding level.
Maybe someone here has the expertise in server management to offer you a solution.

Best regards, Șerban.