HTTP Status Codes
Reference

What each HTTP status code means, why it happens, and how to fix it. Written for developers who need answers, not spec jargon.

2xx Success

200OK

Request succeeded

201Created

Resource created

204No Content

Success, no body

3xx Redirection

301Moved Permanently

Permanent redirect

302Found

Temporary redirect

304Not Modified

Cached version is current

4xx Client Errors

400Bad Request

Malformed request

401Unauthorized

Authentication required

403Forbidden

Access denied

404Not Found

Resource doesn't exist

405Method Not Allowed

Wrong HTTP method

408Request Timeout

Server timed out waiting

409Conflict

Conflicts with current state

410Gone

Permanently removed

413Payload Too Large

Request body too big

415Unsupported Media Type

Wrong content type

422Unprocessable Entity

Validation failed

429Too Many Requests

Rate limited

451Unavailable For Legal Reasons

Censored

5xx Server Errors

500Internal Server Error

Generic server failure

502Bad Gateway

Invalid upstream response

503Service Unavailable

Overloaded or in maintenance

504Gateway Timeout

Upstream didn't respond in time

520Web Server Returns Unknown Error

Cloudflare-specific

522Connection Timed Out

Cloudflare can't reach origin

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