do-release-upgradeinternetnetworkingPROXYupgrade
When I want to upgrade Ubuntu from 18.04 Bionic Beaver to 18.10 to Cosmic Cuttlefish via terminal with sudo do-release-upgrade -d command it gives me warning:
Failed to connect to https://changelogs.ubuntu.com/meta-release-development.
Check your Internet connection or proxy settings.
However I have internet connection, I write this question now from my Ubuntu computer.
How can I resolve this?
Try SSH tunneling/port forwarding. There is a lot of information in Internet. Read this: SSH/OpenSSH/PortForwarding and SSH tunneling with ubuntu.
I like to use SSH socks-proxy. Install plink:
sudo apt install plink
Run command in your local computer (SSH client) with restricted access to Internet:
plink -ssh 111.111.11.111 -C -N -l user -D 127.0.0.1:8081
where 111.111.11.111 - IP-address of your remote SSH-server with unrestricted access and user - your SSH-server username.
Thats all. Now you have SOCKS proxy - all of the traffic through the proxy will be encrypted and routed through your remote SSH-server. Settings for the proxy are: host 127.0.0.1, port 8081.
Add this settings as Ubuntu system-wide proxy settings and instruct browsers, bash etc. to use system proxy. It's possible to add system proxy with Ubuntu System Settings GUI (mine has Ukrainian locale):
If you want to use the proxy for apt, read Configure proxy for APT?, only take into account you have socks-proxy, thus the proxy URLs should be socks4://127.0.0.1:8081 or socks5://127.0.0.1:8081 instead of http://127.0.0.1:8081, for example:
export http_proxy="socks4://127.0.0.1:8081"
Best Answer
It seems like there is an issue about certificates:
As a workaround, I edited the file
/usr/lib/python3/dist-packages/UpdateManager/Core/MetaRelease.pyand added these lines to the beginning: