How to fix "the repository doesn't have a Release file"?

Question

linux

sudo apt-get update gives (below is an excerpt related to the problem)

Err:18 http://screenshots.getdeb.net xenial-getdeb/apps i386 Packages
 Cannot initiate the connection to screenshots.getdeb.net:80 (2400:cb00:2048:1::681c:187d). - connect (101: Network is unreachable) [IP: 2400:cb00:2048:1::681c:187d 80]
Fetched 306 kB in 2s (104 kB/s)
Reading package lists... Done
W: The repository 'http://archive.getdeb.net/ubuntu xenial-getdeb Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://screenshots.getdeb.net/dists/xenial-getdeb/apps/binary-i386/Packages  Cannot initiate the connection to screenshots.getdeb.net:80 (2400:cb00:2048:1::681c:187d). - connect (101: Network is unreachable) [IP: 2400:cb00:2048:1::681c:187d 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.

Please tell me how to fix this.

Answer 1

the repository doesn't have a Release file - this is not an error but a warning. Error next:
The resolver gives you an IPv6 address, which doesn't seem to work for you.
If you do not need IPv6, disable it in the network settings. If needed, see why it doesn't work.