Today I got this error when using github:
$ git pull origin master
# Agent admitted failure to sign using the key.
# debug1: No more authentication methods to try.
# Permission denied (publickey).
I googled it and found the solution here.
For most users, simply running ssh-add to load your keys into the SSH agent will fix this issue.
Enter passphrase for /home/you/.ssh/id_rsa: [tippy tap]
# Identity added: /home/you/.ssh/id_rsa (/home/you/.ssh/id_rsa)
If your key does not have the default filename, you’ll have to pass the path to “ssh-add”
$ ssh-add ~/.ssh/my_other_key
# Enter passphrase for /home/you/.ssh/my_other_key: [tappity tap tap]
# Identity added: /home/you/.ssh/my_other_key (/home/you/.ssh/my_other_key)
The interesting part of this error is: it only happens in Debian/Ubuntu systems.