How to fix LFS: Client error: https://lfs.github.com/objects Authentication required in Git

First, diagnose the issue by examining your Git LFS configuration:

# Check Git LFS version and configuration
git lfs env

# Check Git configuration
git config -l | grep -E "(credential|lfs)"

# View the last error from Git LFS
git lfs logs last

Look for:
- The Endpoint URL Git LFS is trying to reach
- Whether a credential helper is configured
- Any SSH or HTTPS-related settings

If you see no credential helper configured, that's likely the issue.

Set up credential caching so Git LFS can reuse your authentication:

On macOS (using Keychain):

git config --global credential.helper osxkeychain

On Windows (using Git Credential Manager):

git config --global credential.helper manager-core
# Or for older versions:
git config --global credential.helper wincred

On Linux (using cache with timeout):

# Cache credentials in memory for 1 hour (3600 seconds)
git config --global credential.helper 'cache --timeout=3600'

On Linux (persistent storage with libsecret):

# Install libsecret (Ubuntu/Debian)
sudo apt-get install libsecret-1-0 libsecret-1-dev
cd /usr/share/doc/git/contrib/credential/libsecret
sudo make
git config --global credential.helper /usr/share/doc/git/contrib/credential/libsecret/git-credential-libsecret

After configuring, try your Git LFS operation again - you'll be prompted once for credentials which will then be cached.

GitHub (and most Git hosts) require personal access tokens instead of passwords for HTTPS Git operations.

Create a GitHub PAT:

1. Go to GitHub.com -> Settings -> Developer settings -> Personal access tokens -> Tokens (classic)
2. Click "Generate new token (classic)"
3. Give it a descriptive name like "Git LFS access"
4. Select scopes: repo (full control of private repositories) - this includes LFS access
5. Click "Generate token"
6. Copy the token immediately - you won't see it again!

Use the PAT:

When prompted for credentials during Git LFS operations:
- Username: Your GitHub username
- Password: Your personal access token (NOT your GitHub password)

Store the PAT in your credential helper:

# This will prompt for credentials and store them
git config --global credential.helper store
git lfs pull
# Enter username and PAT when prompted

Note: credential.helper store saves credentials in plaintext. For better security, use a credential manager (see previous step).

SSH authentication often works more reliably with Git LFS and doesn't require credential caching.

Check if you have an SSH key:

ls -la ~/.ssh/id_ed25519.pub
# or
ls -la ~/.ssh/id_rsa.pub

Generate a new SSH key if needed:

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

Add your SSH key to GitHub:

1. Copy your public key: cat ~/.ssh/id_ed25519.pub
2. Go to GitHub -> Settings -> SSH and GPG keys -> New SSH key
3. Paste the key and save

Change your remote to use SSH:

# Check current remote
git remote -v

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

Test SSH connection:

ssh -T [email protected]

Now try your Git LFS operation again.

Sometimes the LFS URL gets misconfigured. Check and reset it:

# Check current LFS configuration
git config -l | grep lfs

# Check if lfs.url is set (it usually shouldn't be)
git config lfs.url

If lfs.url is incorrectly set, remove it:

# Remove local lfs.url setting
git config --unset lfs.url

# Remove global lfs.url setting if present
git config --global --unset lfs.url

Git LFS should auto-discover the correct URL from your Git remote. The URL should be derived as <remote-url>/info/lfs, not set manually to something like lfs.github.com.

Verify the fix:

git lfs env
# Should show correct endpoint derived from your remote

Ensure you have the correct permissions for both the repository and its LFS storage:

Check your access level:

# For GitHub, check if you can access the repository
gh repo view owner/repo

Common permission scenarios:

1. Public repository, LFS files: You should be able to pull without authentication, but pushing requires write access
2. Private repository: You need at least read access; pushing requires write access
3. Forked repository: You may need to configure LFS for your fork separately

For GitHub:
- Go to the repository Settings -> Collaborators to verify your access level
- For organizations, check if you're a member with appropriate permissions

For GitLab:
- Check project members and your role
- Ensure Git LFS is enabled in repository settings

If you're a collaborator but still get errors:

# Clear any cached bad credentials
git credential reject
# Then enter:
protocol=https
host=github.com
# Press Ctrl+D

# Try again
git lfs pull

Enable verbose logging to identify exactly where authentication fails:

# Enable Git tracing
GIT_TRACE=1 GIT_CURL_VERBOSE=1 git lfs pull

# Or for more LFS-specific debugging
GIT_TRACE=1 git lfs pull 2>&1 | grep -i auth

Check the LFS logs:

git lfs logs last

Common issues revealed by debugging:

1. 401 Unauthorized: Credentials not sent or invalid
2. 403 Forbidden: Valid credentials but insufficient permissions
3. 407 Proxy Authentication Required: Corporate proxy needs authentication

For proxy issues:

# Configure proxy for Git
git config --global http.proxy http://proxy.example.com:8080
git config --global https.proxy https://proxy.example.com:8080

# For authenticated proxy
git config --global http.proxy http://username:[email protected]:8080

Older versions of Git LFS may have authentication bugs or incompatibilities:

Check current version:

git lfs version

Update on macOS (Homebrew):

brew upgrade git-lfs
git lfs install

Update on Ubuntu/Debian:

curl -s https://packagecloud.io/install/repositories/github/git-lfs/script.deb.sh | sudo bash
sudo apt-get install git-lfs
git lfs install

Update on Windows:

# Using winget
winget upgrade GitHub.GitLFS

# Or using Chocolatey
choco upgrade git-lfs

Verify the update:

git lfs version
git lfs env

Known version-specific issues:
- Git LFS 3.x removed NTLM authentication support (affects Azure DevOps users)
- Some older versions don't properly negotiate with newer LFS servers