HTTP 421 Misdirected Request Error

Why does it happen?

There are several reasons for the 421 error, including:

Reusing a connection that was previously used to communicate with a different server.
Server configuration issues that prevent it from accepting requests from the current client.
Incorrect DNS configuration leading to requests being sent to the wrong server.
Load balancers or reverse proxies routing requests incorrectly within a network.

# Request example 
curl -X POST https://sandbox.oxylabs.io/ -H 'Accept: application/xml;q=0.9' -H 'Accept-Encoding: br' -H 'User-Agent: AppleWebKit/537.36'

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Common fixes

Methods you can try to remedy the error include:

Verify the server configuration to ensure it matches the intended target.
Avoid reusing server connections that may be misdirected.
Check the DNS settings to ensure requests are routed to the correct server.
Implement HTTP/2 server push with care to prevent misdirected requests.

# Response example 
HTTP/1.1 421 Misdirected Request
Content-Type: text/xml; charset=utf-8
Content-Length: 123



421
Misdirected Request

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Common scraping HTTP error codes

401 Unauthorized	403 Forbidden	404 Not found	405 Method not allowed	406 Not acceptable
407 Proxy authentication required	408 Request timeout	409 Conflict	410 Gone	411 Length required
412 Precondition failed	413 Payload too large	414 Uri too long	415 Unsupported media type	416 Range not satisfiable
417 Expectation failed	421 Misdirected request	422 Unprocessable entity	423 Locked	424 Failed dependency
426 Upgrade required	428 Precondition required	429 Too many requests	431 Request header fields too large	444 Connection: close
451 Unavailable for legal reasons	499 Client closed request	501 Not implemented	503 Service unavailable	505 Http version not supported
506 Variant also negotiates	507 Insufficient storage	508 Loop detected	510 Not extended	511 Network authentication required