# HTTP 407 Proxy Authentication Required

HTTP 407 Proxy Authentication Required is the status a proxy returns when a request arrives without valid proxy credentials: no Proxy-Authorization header, a wrong username or password, or a source IP that is not whitelisted when whitelisting is the only method configured. It is the proxy's counterpart of 401 and means the request never left the gateway; fixing the credentials or the whitelist resolves it.


## Common causes

- Credentials pasted with a trailing space or newline.
- Special characters in the password not URL-encoded in a proxy URL.
- The client sends credentials only after a challenge, and the tool does not handle the 407 round trip; pre-emptive `Proxy-Authorization` fixes it.
- A rotated password: the old one expired after the grace period.
- Whitelist mode with a changed source IP.


## Quick check

```bash
curl -v -x http://USER:PASS@res.proxshift.com:9000 https://api.ipify.org
```


## How it works at ProxShift

ProxShift answers 407 with the code invalid_credentials; the dashboard shows the current pair, a rotated password keeps working for ten minutes, and whitelisted addresses need any username to carry parameters.

Source: https://proxshift.com/glossary/http-407