ssh-add could not open a connection to your authentication agent
Related code examples
Add your SSH private key to the ssh-agent. If you created your key with a different name, or if you are adding an existing key that has a different name, replace id_rsa in the command with the name of your private key file.
curl failed to verify the legitimacy of the server and therefore could not establish a secure connection to it.
nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)
could not connect to server: Connection refused Is the server running on host and accepting TCP/IP connections on port 5432?