HTTP Status Codes
HTTP 407 Proxy Authentication Required
Proxy Authentication Required — client must authenticate with a proxy before forwarding the request
What 407 Means
The 407 error on the HTTP Status Codes indicates proxy authentication required — client must authenticate with a proxy before forwarding the request. This typically occurs due to missing or expired proxy authentication credentials.
407 is the proxy equivalent of 401 Unauthorized. The server returns a Proxy-Authenticate header specifying the authentication scheme the client must use.
Technical Background
When a client request passes through an intermediate proxy, that proxy may require authentication before forwarding the request. HTTP 407 signals this requirement by returning a Proxy-Authenticate header.
Unlike 401, which is returned by the origin server and handled transparently by browsers, 407 is often harder for users to diagnose because it involves network infrastructure rather than the destination server.
Common Causes
- Missing or expired proxy authentication credentials
- Client not configured to supply proxy auth headers
- Proxy server requires credentials that the client has not provided
Typical Scenarios
- Enterprise networks with authenticating proxies requiring user credentials
- API clients not configured with proxy authentication settings
- Automated scripts bypassing corporate proxy authentication
What to Know
A 407 error is always between the client and an intermediate proxy, not the origin server. The origin never sees the request until proxy authentication succeeds, making this a network infrastructure issue rather than an application problem.
Frequently Asked Questions
Common questions about HTTP 407 error
401 means the origin server requires authentication. 407 means an intermediate proxy requires authentication before the request reaches the origin server.