Getting HTTP Error 407 - Proxy Authentication Required. How Do I Fix This? or HTTP Error 407: Why Am

http error 407 is all about credentials, so double-check yours.

If you’re on macOS, go to *System Preferences > Network > Advanced > Proxies*.
Enter your proxy details there and make sure "Proxy requires password" is checked.

Also, some proxies use NTLM auth—super annoying. Tools like CNTLM can help bridge the gap if your browser struggles with it.