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Browse common HTTP response codes from 1xx through 5xx with practical debugging context for APIs, browsers, gateways, and automation suites.
| Code | Name | Category | Description | Common Causes | Typical Fix |
|---|---|---|---|---|---|
100 | Continue | 1xx Informational | The server has received the request headers and expects the request body next. | Clients sending large uploads with Expect headers. | Continue streaming the body or remove the Expect header when unnecessary. |
101 | Switching Protocols | 1xx Informational | The server is switching to a different protocol. | WebSocket or HTTP/2 upgrade negotiation. | Verify the Upgrade and Connection headers. |
102 | Processing | 1xx Informational | The server has accepted the request but is still processing it. | Long-running WebDAV operations. | Wait for completion or redesign the endpoint for async work. |
103 | Early Hints | 1xx Informational | The server sends preload hints before the final response. | Resource preload optimization. | Validate Link preload headers. |
200 | OK | 2xx Success | The request succeeded and a response body is returned when applicable. | Standard successful GET, POST, or PATCH handlers. | No fix needed. |
RFC Reference RFC 9110 Real-world Example GET /users returns the users list. Framework Behavior The default success status across frameworks. | |||||
201 | Created | 2xx Success | The request created a new resource. | Successful POST or PUT resource creation. | Return the resource location and payload. |
202 | Accepted | 2xx Success | The request has been accepted for async processing. | Queued jobs or background processing. | Return tracking information for the async task. |
203 | Non-Authoritative Information | 2xx Success | The response succeeded but metadata may come from a transforming proxy. | Proxy transformations or content filtering. | Inspect intermediaries altering responses. |
204 | No Content | 2xx Success | The request succeeded and there is no response body. | Successful DELETE or idempotent update handlers. | Avoid writing a response body. |
205 | Reset Content | 2xx Success | The client should reset its current document view. | Form submissions that require client reset. | Reset client state after processing. |
206 | Partial Content | 2xx Success | The server is returning a byte range of the resource. | Range requests for media or large downloads. | Validate Content-Range and Range headers. |
207 | Multi-Status | 2xx Success | The response contains multiple independent status values. | WebDAV multi-resource operations. | Inspect the per-resource response body. |
208 | Already Reported | 2xx Success | Members of a DAV binding have already been enumerated. | WebDAV propstat responses. | Deduplicate bound resources during traversal. |
226 | IM Used | 2xx Success | The server fulfilled a GET using instance manipulations. | Delta encoding for HTTP responses. | Verify delta support on both client and server. |
300 | Multiple Choices | 3xx Redirect | The resource has multiple possible representations. | Content negotiation or alternate resource variants. | Provide a default or clearer Accept handling. |
301 | Moved Permanently | 3xx Redirect | The resource has permanently moved to a new URL. | Canonical URL migration or domain changes. | Update clients and SEO links to the new URL. |
302 | Found | 3xx Redirect | The resource is temporarily available at a different URL. | Temporary redirects after auth or routing changes. | Use 307 or 303 when method preservation matters. |
303 | See Other | 3xx Redirect | The client should fetch a different URI with GET. | Post/redirect/get patterns. | Return a safe redirect target after writes. |
304 | Not Modified | 3xx Redirect | The cached representation is still valid. | Conditional requests using ETag or If-Modified-Since. | Ensure cache validators are stable and correct. |
305 | Use Proxy | 3xx Redirect | The requested resource must be accessed through a proxy. | Legacy proxy routing requirements. | Avoid using this deprecated status in modern applications. |
307 | Temporary Redirect | 3xx Redirect | The resource is temporarily moved and the method must be preserved. | Maintenance windows or temporary routing changes. | Use when redirecting POST or PUT without changing method. |
308 | Permanent Redirect | 3xx Redirect | The resource moved permanently and the method must be preserved. | Permanent API path or domain migrations. | Update clients and preserve request method. |
400 | Bad Request | 4xx Client Error | The server cannot process the request because it is malformed. | Invalid JSON, missing required params, or bad query syntax. | Validate request payloads and parameter formats before sending. |
401 | Unauthorized | 4xx Client Error | Authentication is required or has failed. | Missing token, expired token, or bad credentials. | Send valid credentials and check auth expiration. |
402 | Payment Required | 4xx Client Error | Reserved for future use and often repurposed by billing systems. | Quota or billing restrictions. | Check subscription state or provider-specific billing rules. |
403 | Forbidden | 4xx Client Error | The server understood the request but refuses to authorize it. | Insufficient role or scope. | Grant the required permission or use a different account. |
404 | Not Found | 4xx Client Error | The requested resource cannot be found. | Wrong URL, deleted resource, or bad route parameters. | Verify the endpoint path and identifiers. |
405 | Method Not Allowed | 4xx Client Error | The request method is not supported for the target resource. | Calling POST on a GET-only endpoint. | Use an allowed method and inspect the Allow header. |
406 | Not Acceptable | 4xx Client Error | The server cannot satisfy the Accept header. | Unsupported response media type requested. | Adjust Accept headers or add serializer support. |
407 | Proxy Authentication Required | 4xx Client Error | The client must authenticate with the proxy. | Corporate proxy or intermediary security layer. | Provide proxy credentials or bypass the proxy. |
408 | Request Timeout | 4xx Client Error | The server timed out waiting for the complete request. | Slow clients or interrupted uploads. | Retry the request or increase timeout thresholds. |
409 | Conflict | 4xx Client Error | The request conflicts with the current state of the resource. | Version mismatch, duplicate resource, or state race. | Refresh the state and retry with conflict resolution. |
410 | Gone | 4xx Client Error | The resource was intentionally removed and is no longer available. | Deleted or sunset endpoints. | Stop calling the endpoint and migrate to the replacement. |
411 | Length Required | 4xx Client Error | The server refuses the request without a Content-Length header. | Required body length missing on uploads. | Send Content-Length or switch to chunked transfer when supported. |
412 | Precondition Failed | 4xx Client Error | One or more request preconditions evaluated to false. | ETag or If-Match mismatch. | Refresh the resource and retry with updated preconditions. |
413 | Content Too Large | 4xx Client Error | The request payload is larger than the server allows. | Large file uploads or oversized JSON bodies. | Reduce payload size or raise upload limits safely. |
414 | URI Too Long | 4xx Client Error | The request target is longer than the server is willing to interpret. | Huge query strings or redirect loops. | Move data into the request body or shorten the URL. |
415 | Unsupported Media Type | 4xx Client Error | The server does not support the request content type. | Sending XML to a JSON-only endpoint. | Set the correct Content-Type and serializer. |
416 | Range Not Satisfiable | 4xx Client Error | The requested range cannot be fulfilled. | Invalid byte ranges for downloads or media. | Request a valid range within the resource bounds. |
417 | Expectation Failed | 4xx Client Error | The server cannot meet the requirements of the Expect header. | Unsupported Expect: 100-continue workflows. | Remove or correct the Expect header. |
418 | I'm a Teapot | 4xx Client Error | A humorous status code indicating the server refuses to brew coffee because it is a teapot. | Easter eggs or non-production demos. | Do not use in production unless intentional. |
421 | Misdirected Request | 4xx Client Error | The request was sent to a server that cannot produce the response. | HTTP/2 connection reuse across the wrong origin. | Retry on a fresh connection or correct TLS/SNI routing. |
422 | Unprocessable Content | 4xx Client Error | The request is syntactically correct but semantically invalid. | Validation failures or domain rule violations. | Fix field-level validation errors and resubmit. |
423 | Locked | 4xx Client Error | The target resource is locked. | Concurrent edit locks or WebDAV resource locking. | Release the lock or retry later. |
424 | Failed Dependency | 4xx Client Error | The request failed because a dependent action failed. | Batch or chained operations. | Inspect the failed prerequisite request. |
425 | Too Early | 4xx Client Error | The server is unwilling to risk replaying the request. | Early data in TLS 1.3 or replay-sensitive operations. | Retry without early data. |
426 | Upgrade Required | 4xx Client Error | The client must switch to a different protocol. | TLS-only services or websocket-only routes. | Upgrade protocol as instructed by the Upgrade header. |
428 | Precondition Required | 4xx Client Error | The origin server requires the request to be conditional. | Optimistic concurrency enforcement. | Send If-Match or similar precondition headers. |
429 | Too Many Requests | 4xx Client Error | The client has sent too many requests in a given amount of time. | Rate limiting or quota exhaustion. | Back off, honor Retry-After, or increase quota. |
431 | Request Header Fields Too Large | 4xx Client Error | The server refuses the request because header fields are too large. | Oversized cookies or excessive custom headers. | Trim headers, cookies, or JWT payload size. |
451 | Unavailable For Legal Reasons | 4xx Client Error | The server is denying access due to legal demands. | Geo restrictions or legal takedowns. | Review policy or legal constraints behind the restriction. |
500 | Internal Server Error | 5xx Server Error | The server encountered an unexpected condition. | Unhandled exceptions, null references, or infrastructure errors. | Inspect logs, stack traces, and failing dependencies. |
501 | Not Implemented | 5xx Server Error | The server does not support the request method or capability. | Unsupported HTTP methods or missing backend behavior. | Implement the endpoint or avoid unsupported methods. |
502 | Bad Gateway | 5xx Server Error | The server received an invalid response from an upstream server. | Reverse proxy, gateway, or upstream crashes. | Inspect upstream health and proxy connectivity. |
503 | Service Unavailable | 5xx Server Error | The server is temporarily unable to handle the request. | Maintenance mode, overload, or dependency outages. | Retry later and check service health or capacity. |
504 | Gateway Timeout | 5xx Server Error | The server did not receive a timely response from upstream. | Slow upstream services or network partitions. | Optimize downstream latency or increase timeout budgets carefully. |
505 | HTTP Version Not Supported | 5xx Server Error | The server does not support the HTTP protocol version used. | Legacy clients or incompatible protocol negotiation. | Switch to a supported HTTP version. |
506 | Variant Also Negotiates | 5xx Server Error | The server has an internal configuration error related to content negotiation. | Recursive or invalid variant configuration. | Fix server-side content negotiation rules. |
507 | Insufficient Storage | 5xx Server Error | The server cannot store the representation needed to complete the request. | Disk exhaustion or quota exhaustion. | Free space, increase quotas, or reduce payload size. |
508 | Loop Detected | 5xx Server Error | The server detected an infinite loop while processing the request. | Recursive bindings or cyclic dependencies. | Fix the recursive reference or dependency cycle. |
510 | Not Extended | 5xx Server Error | Further extensions to the request are required for fulfillment. | Policy extension expectations not met. | Provide the extension or policy parameters required by the server. |
511 | Network Authentication Required | 5xx Server Error | The client needs to authenticate to gain network access. | Captive portals or restricted network gateways. | Complete network login before retrying the request. |
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Tips
Status codes are more useful when paired with likely causes and practical fixes, not just terse RFC names.
This reference surfaces the code, category, likely problem source, and how common frameworks or infrastructure layers usually expose the response.
It is built as a static local dataset so you can use it as a quick keyboard-friendly lookup while debugging API and browser flows.
Yes. Arrow keys move through rows, and Enter expands the active status code.
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