sign_and_send_pubkey: signing failed: agent refused operation

sign_and_send_pubkey: signing failed: agent refused operation

Try to add the private key identities to the authentication agent:

# ssh-add

To see a list of fingerprints of all identities:

# ssh-add -l

Reference:

https://askubuntu.com/questions/762541/ubuntu-16-04-ssh-sign-and-send-pubkey-signing-failed-agent-refused-operation