HTTP 407 Proxy Authentication Required vs 421 Misdirected Request
Both HTTP 407 (Proxy Authentication Required) and 421 (Misdirected Request) belong to the 4xx Client Error category. 407 indicates that the client must first authenticate itself with the proxy. Meanwhile, 421 means that the request was directed at a server that is unable to produce a response for the combination of scheme and authority in the URI.
Description
The client must first authenticate itself with the proxy.
When You See It
When accessing the internet through a corporate proxy that requires authentication.
How to Fix
Configure proxy credentials in your HTTP client or browser settings.
Description
The request was directed at a server that is unable to produce a response for the combination of scheme and authority in the URI.
When You See It
With HTTP/2 when a connection is reused for a domain the certificate doesn't cover.
How to Fix
Retry the request on a new connection.
Key Differences
HTTP 407: The client must first authenticate itself with the proxy.
HTTP 421: The request was directed at a server that is unable to produce a response for the combination of scheme and authority in the URI.
You encounter 407 when when accessing the internet through a corporate proxy that requires authentication.
You encounter 421 when with HTTP/2 when a connection is reused for a domain the certificate doesn't cover.
When to Use Which
For 407 (Proxy Authentication Required): Configure proxy credentials in your HTTP client or browser settings. For 421 (Misdirected Request): Retry the request on a new connection.