Error: Agent admitted failure to sign

When trying to SSH into your GitHub Enterprise Server instance on a Linux computer, you may see the following message in your terminal:

$ ssh -vT git@hostname
> ...
> Agent admitted failure to sign using the key.
> debug1: No more authentication methods to try.
> Permission denied (publickey).

For more details, see this issue report.

Resolution

You should be able to fix this error by loading your keys into your SSH agent with ssh-add:

# start the ssh-agent in the background
$ eval "$(ssh-agent -s)"
> Agent pid 59566
$ ssh-add
> 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 (/.ssh/id_rsa), you'll have to pass that path to ssh-add:

# start the ssh-agent in the background
$ eval "$(ssh-agent -s)"
> Agent pid 59566
$ 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)