Encountering the dreaded “GitHub: Permission denied (publickey). fatal: The remote end hung up unexpectedly” error can be a frustrating roadblock for developers. This specific message indicates a problem with how your local machine is attempting to authenticate with GitHub’s servers, primarily through SSH (Secure Shell) keys. It’s a common hurdle, signaling that your SSH client failed to provide a valid public key that GitHub recognizes, or that the connection itself was abruptly terminated. Understanding the root cause is the first step towards resolving this issue and restoring your seamless workflow. This guide will walk you through the common reasons for this error and provide actionable, step-by-step solutions to get you back to pushing code.

Understanding GitHub’s SSH Authentication Process

The “GitHub: Permission denied (publickey). fatal: The remote end hung up unexpectedly” error is deeply rooted in how GitHub authenticates users for Git operations. Instead of using your GitHub username and password for every push and pull, SSH authentication provides a more secure and convenient method. This system relies on a pair of cryptographic keys: a private key, which resides securely on your local machine, and a corresponding public key, which you upload to your GitHub account. When you attempt to interact with a remote repository, your local SSH client presents the public key to GitHub. If GitHub finds a matching public key associated with your account and the private key on your machine can successfully sign the authentication request, access is granted.

This public key authentication mechanism is robust, but it requires careful setup and management. The private key must be kept secret and have appropriate file permissions, typically 0600 or 0400, preventing other users from reading it. The SSH agent, a background program, often manages these keys, loading them into memory and providing them to your SSH client when needed, often after you’ve entered a passphrase. If any part of this chain is broken – an incorrect public key on GitHub, a missing private key locally, a misconfigured SSH agent, or improper key permissions – the authentication fails, leading directly to the “GitHub permission denied publickey” message.

Common Causes of the Permission Denied Error

The “GitHub: Permission denied (publickey). fatal: The remote end hung up unexpectedly” error can stem from several common issues. One of the most frequent culprits is an incorrectly configured or non-running SSH agent. The SSH agent is responsible for holding your private keys in memory, so you don’t have to re-enter your passphrase every time you connect. If it’s not running or hasn’t loaded your key, your SSH client won’t be able to provide the necessary credentials to GitHub, resulting in a failed connection and the permission denied message. This often happens after a system restart or if you’ve closed your terminal session.

Another prevalent cause is a mismatch between the public key registered with GitHub and the private key on your local machine. Perhaps you’re using an old key, a different key than the one uploaded, or you simply haven’t added your current public key to your GitHub account settings at all. File permissions on your private key are also critical; if they are too permissive (e.g., world-readable), SSH will consider the key insecure and refuse to use it. Furthermore, a crucial detail often overlooked is ensuring your SSH client is actually using the correct key for GitHub. This might involve checking your ~/.ssh/config file to ensure specific host entries are directing traffic to the right key. Firewall restrictions or network issues, though less common for this specific error, can also prevent the SSH connection from fully establishing, leading to the “remote end hung up unexpectedly” part of the message.

According to GitHub’s official documentation, ensuring your SSH key is properly added to the ssh-agent and that the public key is registered on GitHub are the most vital steps for successful authentication. GitHub’s guide on connecting with SSH provides comprehensive instructions for these processes, highlighting their importance in preventing access issues.

Resolving the “GitHub: Permission denied (publickey). fatal: The remote end hung up unexpectedly” error often involves a systematic check of your SSH configuration. If you’re facing this issue, follow these steps to diagnose and fix it. Many users find success by simply ensuring their SSH agent is running and has the correct key loaded. This featured snippet optimized paragraph provides a concise answer: To fix “GitHub permission denied publickey,” first verify your SSH agent is running and has your key loaded using ssh-add -l. If not, start the agent with eval "$(ssh-agent -s)" and add your key with ssh-add ~/.ssh/id_rsa. Next, confirm your public key is added to your GitHub account and that local key permissions are set correctly to chmod 600 ~/.ssh/id_rsa.

1. **Verify Your SSH Agent is Running and Has Your Key:**Open your terminal and run ssh-add -l. This command lists the SSH keys currently loaded into your agent. If you see “The agent has no identities,” or if your key isn’t listed, the agent isn’t running or hasn’t loaded your key. To start the agent and add your key:

   • Start the SSH agent: eval "$(ssh-agent -s)" (for Linux/macOS) or Get-Service ssh-agent | Start-Service (for Windows PowerShell).
   • Add your private key (replace id_rsa with your key’s filename if different): ssh-add ~/.ssh/id_rsa. You might be prompted for your passphrase.

2. **Check Your GitHub SSH Keys:**Log in to your GitHub account and navigate to Settings > SSH and GPG keys. Ensure that the public key corresponding to your local private key is listed there. If it’s not, you’ll need to add it. You can get your public key by running cat ~/.ssh/id_rsa.pub in your terminal and copying the output.

3. **Inspect SSH Key File Permissions:**Incorrect file permissions for your private key are a common security measure that can trigger this error. Your private key file (e.g., ~/.ssh/id_rsa) should have permissions that only allow you to read and write to it. Run the following command to set the correct permissions:

   chmod 600 ~/.ssh/id_rsaAlso, ensure your ~/.ssh directory has appropriate permissions: chmod 700 ~/.ssh.

4. **Test Your SSH Connection to GitHub:**After performing the above steps, test your connection by running: ssh -T git@github.com. If successful, you should see a message like “Hi [YOUR_USERNAME]! You’ve successfully authenticated, but GitHub does not provide shell access.” This confirms your SSH setup is working correctly for GitHub.

5. **Review Your Git Remote URL:**Ensure your Git remote URL is configured to use SSH, not HTTPS. In your repository, run git remote -v. If it shows an HTTPS URL (e.g., https://github.com/user/repo.git), you need to change it to SSH (e.g., git@github.com:user/repo.git). Use the command: git remote set-url origin git@github.com:user/repo.git.

Advanced Troubleshooting and Best Practices

When the standard solutions don’t resolve the “GitHub: Permission denied (publickey). fatal: The remote end hung up unexpectedly” error, it’s time to delve into more advanced troubleshooting. One area to investigate is your SSH configuration file, located at ~/.ssh/config. This file allows you to define specific settings for different hosts, Question & Answer :

I have followed these instructions below to upload a project.

Global setup:

Download and install Git git config --global user.name "Your Name" git config --global user.email <a class="__cf_email__" data-cfemail="4c38253e29222b2d0c2b212d2520622f2321" href="/cdn-cgi/l/email-protection">[email protected]</a> Add your public key Next steps: mkdir tirengarfio cd tirengarfio git init touch README git add README git commit -m 'first commit' git remote add origin <a class="__cf_email__" data-cfemail="e0878994a0878994889582ce838f8d" href="/cdn-cgi/l/email-protection">[email protected]</a>:tirenga/tirenga.git git push origin master 

But I get this error:

Permission denied (publickey). fatal: The remote end hung up unexpectedly

I had to add my public key to github. https://help.github.com/articles/generating-ssh-keys