I just wanted to add a comment, for any others who come to this via Google.
I also hit this exact same error, but it turned out not to be caused directly by the network proxy. I had just run apt-add-repository, and that had failed to import the GPG key:
root@buildhost:/home/mblokzij/ws-qvpc# add-apt-repository ppa:x2go/stable
Quick howto to turn your machine into an X2Go server:
...
gpg: keyring `/tmp/tmpf3fzey4y/secring.gpg' created
gpg: keyring `/tmp/tmpf3fzey4y/pubring.gpg' created
gpg: requesting key 0A53F9FD from hkp server keyserver.ubuntu.com
gpgkeys: key A7D8D681B1C07FE41499323D7CDE3A860A53F9FD can't be retrieved
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
Note the last line.
After manually importing the key, apt-get update ran fine. I used:
I just wanted to add a comment, for any others who come to this via Google.
I also hit this exact same error, but it turned out not to be caused directly by the network proxy. I had just run apt-add-repository, and that had failed to import the GPG key:
root@buildhost: /home/mblokzij/ ws-qvpc# add-apt-repository ppa:x2go/stable 4y/secring. gpg' created 4y/pubring. gpg' created ubuntu. com 41499323D7CDE3A 860A53F9FD can't be retrieved
Quick howto to turn your machine into an X2Go server:
...
gpg: keyring `/tmp/tmpf3fzey
gpg: keyring `/tmp/tmpf3fzey
gpg: requesting key 0A53F9FD from hkp server keyserver.
gpgkeys: key A7D8D681B1C07FE
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
Note the last line.
After manually importing the key, apt-get update ran fine. I used:
apt-key adv --recv-keys --keyserver keys.gnupg.net 0A53F9FD
I realise I used a different keyserver, but I copy/pasted the key id from the logs above.