How to fix remote: Support for password authentication was removed. Please use a personal access token instead. in Git

1. Log into GitHub and click your profile picture, then select Settings
2. In the left sidebar, scroll down and click Developer settings
3. Click Personal access tokens > Tokens (classic)
4. Click Generate new token > Generate new token (classic)
5. Add a descriptive note (e.g., "Git CLI access")
6. Set an expiration (or "No expiration" for long-lived tokens)
7. Select scopes - for typical Git operations, check:
- repo (Full control of private repositories)
- workflow (if you work with GitHub Actions)
8. Click Generate token
9. Copy the token immediately - you won't be able to see it again

# Your token will look something like this:
ghp_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Remove old cached passwords so Git prompts for the new token.

macOS (Keychain Access):

# Option 1: Use command line
git credential-osxkeychain erase
host=github.com
protocol=https
# Press Enter twice

# Option 2: Open Keychain Access app, search for "github.com", delete the entry

Windows (Credential Manager):
1. Open Control Panel > Credential Manager
2. Click Windows Credentials
3. Find entries for git:https://github.com or github.com
4. Click the entry and select Remove

Linux (Git Credential Cache):

# Clear cached credentials
git credential reject
host=github.com
protocol=https
# Press Enter twice

# Or remove the credential helper cache file
rm ~/.git-credentials

The next time you run a Git command that requires authentication, enter your credentials:

git push origin main
# Username: your-github-username
# Password: ghp_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx  # Paste your token here

Important: When prompted for a "password", paste your personal access token, not your GitHub account password.

To avoid entering the token repeatedly, configure a credential helper:

macOS (uses Keychain):

git config --global credential.helper osxkeychain

Windows (uses Credential Manager):

git config --global credential.helper manager

Linux (cache in memory for 1 hour):

git config --global credential.helper 'cache --timeout=3600'

Linux (store permanently in file):

git config --global credential.helper store
# Note: This stores credentials in plain text at ~/.git-credentials

SSH keys are another secure authentication method that doesn't require tokens:

# Check for existing SSH keys
ls -la ~/.ssh

# Generate a new SSH key (if needed)
ssh-keygen -t ed25519 -C "[email protected]"

# Start the SSH agent and add your key
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

# Copy the public key
cat ~/.ssh/id_ed25519.pub
# Copy the output

Add the key to GitHub:
1. Go to Settings > SSH and GPG keys
2. Click New SSH key
3. Paste your public key and save

Update your remote URL to use SSH:

# Check current remote
git remote -v

# Change from HTTPS to SSH
git remote set-url origin [email protected]:username/repository.git