Required Header Missing¶

Type URI: https://arcp.0x001.tech/docs/problems/required-header-missing
HTTP Status: 400 Bad Request
Title: Required Header Missing

Description¶

This problem occurs when a required HTTP header is missing from the request.

Example Response¶

{
  "type": "https://arcp.0x001.tech/docs/problems/required-header-missing",
  "title": "Required Header Missing",
  "status": 400,
  "detail": "Required header 'X-Client-Fingerprint' is missing",
  "instance": "/auth/login",
  "timestamp": "2024-01-15T10:30:00Z",
  "request_id": "req_header123",
  "missing_header": "X-Client-Fingerprint"
}

Common Missing Headers¶

X-Client-Fingerprint¶

Required for admin login to bind sessions:

# Missing header (fails)
curl -X POST "http://localhost:8001/auth/login" \
  -H "Content-Type: application/json" \
  -d '{"username": "admin", "password": "pass"}'

# With required header (works)
curl -X POST "http://localhost:8001/auth/login" \
  -H "Content-Type: application/json" \
  -H "X-Client-Fingerprint: unique-session-id" \
  -d '{"username": "admin", "password": "pass"}'

Authorization Header¶

Required for protected endpoints:

# Missing auth header (fails)
curl "http://localhost:8001/agents"

# With auth header (works)
curl "http://localhost:8001/agents" \
  -H "Authorization: Bearer <token>"

Resolution Steps¶

1. Add Missing Header¶

Include the required header in your request.

2. Check API Documentation¶

Review endpoint documentation for required headers.

3. Using ARCP Client (Headers Managed Automatically)¶

import asyncio
from arcp import ARCPClient, AuthenticationError

async def header_management_example():
    """ARCP client automatically manages required headers"""

    # The client handles all required headers automatically
    async with ARCPClient("http://localhost:8001") as client:
        try:
            # Client automatically adds X-Client-Fingerprint and other headers
            await client.login_admin("admin", "your-password")
            print("Login successful - headers handled automatically")

            # All subsequent requests include proper headers
            agents = await client.list_agents()
            print(f"Retrieved {len(agents)} agents")

        except AuthenticationError as e:
            if "header" in str(e).lower():
                print(f"Header issue: {e}")
                print("This should not happen with the ARCP client as headers are automatic")
            else:
                print(f"Authentication error: {e}")

if __name__ == "__main__":
    asyncio.run(header_management_example())