HTTP/4xx (Client Error)
407 Proxy Authentication Required
The client must first authenticate itself with the proxy.
❓ Why does this happen?
Corporate HTTP proxies require credentials (Proxy-Authorization header) before allowing outbound traffic, breaking npm, git, or Docker pulls.
✅ How to fix it
Configure proxy credentials: npm config set proxy http://user:pass@proxy:8080 or export HTTPS_PROXY with credentials.
Return or handle 407 in your stack
// app/api/resource/route.ts
export function GET() {
return Response.json(
{ error: "Proxy Authentication Required", status: 407 },
{
status: 407
}
);
}Live 407 mock endpoint
Point your app, tests, or retry logic at this free public URL to reproduce a real 407 response (CORS enabled, optional ?delay=ms up to 5000).
https://castov.com/api/mock/407407 vs similar status codes
Frequently Asked Questions
What does HTTP Status 407 mean?
Why am I getting a 407 status code?
How do I fix a 407 Proxy Authentication Required error?
What is the difference between 407 Proxy Authentication Required and 401 Unauthorized?
How can I test how my app handles a 407 response?
Other 4xx status codes
Browse the full HTTP status codes directory or troubleshoot terminal errors in the Error Fix Encyclopedia.