What does "Permission denied (publickey)" mean?

It means the SSH handshake with the server failed: GitHub (or GitLab, Bitbucket) did not receive a private key matching any public key registered on your account. Git never even got to check repository permissions.

I added my key to GitHub but it still fails. Why?

Three common causes: you pasted the private key instead of the .pub file, the key is not loaded in your SSH agent (run "ssh-add ~/.ssh/id_ed25519"), or SSH is offering a different key. Run "ssh -T git@github.com -v" to see which keys are tried.

Should I use SSH or HTTPS with GitHub?

Both are fine. SSH avoids typing credentials once your key is set up. HTTPS with a personal access token or a credential manager is simpler on shared or corporate machines. You can switch anytime with "git remote set-url".

Is it safe to share my .pub file?

Yes. The .pub file is the public half of the key pair and is meant to be shared. Never share the private key (the file without .pub), and protect it with a passphrase if the machine is shared.

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git@github.com: Permission denied (publickey)

This error means GitHub rejected your SSH connection because it could not authenticate you with a key. Your code is safe. You just need to set up an SSH key once, and it takes five minutes.

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Error explained

What this error means

When you use an SSH URL like git@github.com:team/project.git, Git authenticates with an SSH key pair instead of a password. GitHub checks whether your machine offers a private key matching a public key registered on your account. If no key matches, the connection is refused before Git can do anything.

gitquest terminal: permission denied

$git clone git@github.com:team/project.git

Cloning into 'project'...

git@github.com: Permission denied (publickey).

fatal: Could not read from remote repository.

Please make sure you have the correct access rights

and the repository exists.

Root causes

Why this happens

No SSH key on this machine

A fresh laptop or a new user account has no key pair in ~/.ssh. GitHub has nothing to match against, so every SSH connection is rejected.

Key not added to GitHub

You generated a key but never registered the public half on GitHub. The key exists locally, but GitHub does not know it belongs to your account.

Agent not offering the key

The key exists and is on GitHub, but the SSH agent is not loaded with it, or SSH offers another key first. Common after a reboot or on machines with several keys.

Step-by-step fix

How to fix it

Generate a key, add it to the agent and to GitHub, then test. You only do this once per machine.

Generate and load a key

Check for an existing key first. If there is none, create an Ed25519 key and add it to the agent.

gitquest terminal: create the key

# 1. Check if you already have a key

$ls -al ~/.ssh

# Look for id_ed25519.pub or id_rsa.pub

# 2. If not, generate one

$ssh-keygen -t ed25519 -C "you@example.com"

Your public key has been saved in ~/.ssh/id_ed25519.pub

# 3. Add it to the SSH agent

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

$ssh-add ~/.ssh/id_ed25519

Identity added: /Users/you/.ssh/id_ed25519

Register on GitHub and test

Copy the public key to GitHub, then verify with ssh -T.

gitquest terminal: add and test

# 4. Copy the PUBLIC key (.pub file)

$cat ~/.ssh/id_ed25519.pub

ssh-ed25519 AAAAC3NzaC1lZDI1... you@example.com

# Paste it on GitHub > Settings > SSH and GPG keys > New SSH key

# 5. Test the connection

$ssh -T git@github.com

Hi you! You've successfully authenticated, but GitHub does not provide shell access.

No SSH? Use HTTPS instead

If you cannot use SSH (locked-down network, shared machine), switch the remote to HTTPS and authenticate with a personal access token or credential manager.

gitquest terminal: HTTPS alternative

# Alternative: switch the remote to HTTPS

$git remote set-url origin https://github.com/team/project.git

$git remote -v

origin https://github.com/team/project.git (fetch)

origin https://github.com/team/project.git (push)

# Git will then authenticate with a token instead of SSH

Best practices

How to prevent it

One key per machine

Generate a dedicated key on each computer you use and register each one on GitHub. Never copy private keys between machines.

Test after any change

After an OS update, a reinstall, or a new key, run ssh -T git@github.com before you need to push something urgent.

Use a passphrase and the agent

Protect the private key with a passphrase and let the SSH agent (or your OS keychain) remember it. Security without retyping.

Related commands

git clone

Copy a remote repository locally

git remote

Manage remote repository URLs

git push

Send your commits to the remote

GitQuest is created by Anaïs (nouvelle fenêtre), web developer and head of education, specializing in tech training and digital accessibility.

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