How to fix Error connecting to agent: No such file or directory in SSH

First, verify whether an SSH agent process exists:

ps aux | grep ssh-agent

You should see a line like:

user  12345  0.0  0.1  8192  1024 ?  Ss  10:30  0:00  ssh-agent

If no ssh-agent process appears, the agent is not running. Proceed to step 2 to start it.

If the agent is running, check the SSH_AUTH_SOCK variable:

echo $SSH_AUTH_SOCK

It should output something like /tmp/ssh-XXXXXXXXXX/agent.12345 or /run/user/1000/ssh-agent.socket. If it's empty or unset, proceed to step 2.

The most reliable way to start SSH agent in a new terminal session is:

eval "$(ssh-agent -s)"

This command:
1. Starts a new SSH agent process
2. Outputs shell commands to set environment variables (SSH_AUTH_SOCK, SSH_AGENT_PID)
3. eval executes those commands in your current shell

After running this, verify it worked:

echo $SSH_AUTH_SOCK
ssh-add -l

The second command should return either your loaded keys or "The agent has no identities" (which is fine—it just means no keys are loaded yet).

On macOS/BSD, use -K flag instead of -s:

eval "$(ssh-agent -K)"

Once the agent is running, load your SSH private key:

ssh-add ~/.ssh/id_rsa

If your key has a different name or location:

ssh-add ~/.ssh/my-custom-key
ssh-add ~/.ssh/github-key

You'll be prompted for the key's passphrase (if it has one). After entering it, the key is now loaded in the agent.

Verify the key is loaded:

ssh-add -l

Should show output like:

2048 SHA256:abcdef... user@host (RSA)

To avoid running eval ssh-agent in every new terminal, add it to your shell startup file.

For bash, add to ~/.bashrc:

if [ -z "$SSH_AUTH_SOCK" ]; then
  eval "$(ssh-agent -s)"
  ssh-add ~/.ssh/id_rsa 2>/dev/null
fi

For zsh, add to ~/.zshrc:

if [ -z "$SSH_AUTH_SOCK" ]; then
  eval "$(ssh-agent -s)"
  ssh-add ~/.ssh/id_rsa 2>/dev/null
fi

For fish, add to ~/.config/fish/config.fish:

if not set -q SSH_AUTH_SOCK
  eval (ssh-agent -c)
  ssh-add ~/.ssh/id_rsa 2>/dev/null
end

The condition [ -z "$SSH_AUTH_SOCK" ] ensures the agent is only started once per session. After adding this, reload your shell:

source ~/.bashrc

On Linux systems with GNOME 46.1+, GNOME Keyring disabled SSH by default, causing SSH_AUTH_SOCK to not be set.

Step 1: Enable the gcr-ssh-agent socket:

systemctl --user enable gcr-ssh-agent.socket
systemctl --user start gcr-ssh-agent.socket

Step 2: Set SSH_AUTH_SOCK environment variable persistently:

mkdir -p ~/.config/environment.d
echo "SSH_AUTH_SOCK=$XDG_RUNTIME_DIR/gcr/ssh" > ~/.config/environment.d/ssh_auth.conf

Step 3: Log out and back in (or restart your desktop session) for changes to take effect.

Verify it's working:

echo $SSH_AUTH_SOCK
ssh-add -l

Sometimes SSH_AUTH_SOCK points to a different path than the actual agent socket.

Check what the agent is actually using:

ps aux | grep ssh-agent | grep -v grep

And check what SSH_AUTH_SOCK is set to:

echo $SSH_AUTH_SOCK

If they don't match, try killing the agent and restarting it:

pkill ssh-agent
eval "$(ssh-agent -s)"

For systemd user service setup, if you're using a service unit, ensure your SSH_AUTH_SOCK is correctly set. For example, add to your service unit file:

[Service]
Environment="SSH_AUTH_SOCK=%t/ssh"

Or set it in environment.d files:

echo "SSH_AUTH_SOCK=$XDG_RUNTIME_DIR/ssh" > ~/.config/environment.d/sshauth.conf

On Windows, SSH agent setup is different.

Step 1: Start the SSH Agent service:

# Run PowerShell as Administrator
Set-Service ssh-agent -StartupType Automatic
Start-Service ssh-agent
Get-Service ssh-agent

Step 2: Add your key using ssh-add:

ssh-add C:\Users\YourUsername\.ssh\id_rsa

Step 3: Verify it works:

ssh-add -l

If ssh-add still fails, ensure you're using Windows' native OpenSSH (not Git Bash's bundled version). Use the full path:

C:\Windows\System32\OpenSSH\ssh-add.exe -l

If that works but regular ssh-add doesn't, add the Windows OpenSSH directory to your PATH environment variable.