How to fix “permission denied” error on GitHub?

 
Step 1: Understand the “Permission Denied” Error
 

When you run a Git command that communicates with GitHub over SSH (for example git push), you may see an error like:

Permission denied (publickey).
fatal: Could not read from remote repository.

This means GitHub didn’t accept your SSH key. The most common causes are:

• You don’t have an SSH key on your machine.
• Your SSH key is not loaded into the SSH agent.
• Your SSH key is not added to your GitHub account.
• Your Git remote is using the wrong URL format.
• Your private key file has incorrect permissions.

 
Step 2: Check for Existing SSH Keys
 

Verify if you already have SSH keys in your local machine:

ls -al ~/.ssh

Common key file names are id_rsa and id_rsa.pub or id_ed25519 and id_ed25519.pub. If you see at least one .pub file, you have an existing public key.

• If you have a public key, go to Step 4.
• If no keys exist, proceed to Step 3 to generate one.

 
Step 3: Generate a New SSH Key
 

Create a new SSH key using the ssh-keygen command:

ssh-keygen -t ed25519 -C "your\[email protected]"

When prompted:

• Press Enter to accept the default file location.
• Optionally provide a passphrase or press Enter for no passphrase.

This produces two files: your private key (~/.ssh/id_ed25519) and your public key (~/.ssh/id_ed25519.pub).

 
Step 4: Add Your SSH Key to the SSH Agent
 

Ensure the SSH agent is running and your key is loaded:

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id\_ed25519

• If you used a different filename, replace `id_ed25519` with your key’s name.
• On Windows, you may need to start the SSH agent as a service or via Git Bash.

 
Step 5: Add Your SSH Key to Your GitHub Account
 

Copy the contents of your public key and add it to GitHub settings:

cat ~/.ssh/id\_ed25519.pub

• Log in to GitHub and go to **Settings → SSH and GPG keys → New SSH key**.
• Paste the key, give it a descriptive title, and click **Add SSH key**.

 
Step 6: Update Your Git Remote to Use SSH
 

Verify your remote URL and switch to SSH if needed:

git remote -v

If you see an HTTPS URL (https://github.com/...), change it to SSH:

git remote set-url origin [email protected]:username/repo.git

Replace username/repo.git with your repository’s path.

 
Step 7: Test the SSH Connection
 

Run a test command to confirm authentication:

ssh -T [email protected]

• A successful message looks like: Hi username! You've successfully authenticated...
• If you still see “Permission denied,” proceed to Step 8.

 
Step 8: Fix File Permissions on Your Private Key
 

SSH requires strict permissions on your private key. Ensure only you can read it:

chmod 600 ~/.ssh/id\_ed25519

Then repeat Step 7 to test the connection again.

 
Step 9: Alternative—Use HTTPS or Personal Access Token
 

If SSH still fails, you can switch back to HTTPS and use a Personal Access Token (PAT):

git remote set-url origin https://github.com/username/repo.git

• Generate a PAT under **Settings → Developer settings → Personal access tokens**.
• Use the token instead of your password when Git prompts you.

You have now resolved the “Permission denied” error and can push, pull, and clone repositories on GitHub without issues.