GitHub MCP Server Authentication Error Troubleshooting Guide

Overview

Unauthorized or Bad credentials are the most common authentication errors for GitHub MCP servers [^1]. This usually indicates incorrect Personal Access Token (PAT) configuration or insufficient permissions.

Error Symptoms

Authentication Failed: Bad credentials
Error: Unauthorized

Common Causes and Solutions

Cause 1: Incorrect Token Format

Solution: Ensure using the correct token format. GitHub supports multiple token formats:

• ghp_ - Personal Access Token
• github_pat_ - Fine-grained Personal Access Token
• gho_ - OAuth Token

Cause 2: Insufficient Token Permissions

Solution: Check token permissions in GitHub Settings > Developer settings > Personal access tokens, ensure necessary repository access permissions are included [^2].

Cause 3: Token Expired

Solution: Check if token has expired, regenerate if necessary [^3].

Cause 4: Incorrect Configuration Location

Solution: Ensure correct configuration in Claude Code config file:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "ghp_xxxxxxxxxxxx"
      }
    }
  }
}

Verify Token Validity

Test token using curl:

curl -H "Authorization: Bearer YOUR_TOKEN" https://api.github.com/user

Reference Sources

[^1]: GitHub Issue #19281 - GitHub MCP Server authentication failure discussion
[^2]: GitHub Docs - Creating a personal access token - Official token creation guide
[^3]: DEV Community - GitHub Token Expiry Issue - Token expiration analysis