HTTP status codes: what they mean and what to check

Client can continue sending the request body after interim acknowledgment. [1][2]

Server agrees to a negotiated protocol switch such as a supported upgrade. [1][2]

WebDAV extension indicates a request is still being handled. [1][2]

Preliminary header hints can let clients preload linked resources. [1][2]

Ordinary success; actual representation or result depends on request method. [1][2]

New resource created; check Location or returned representation where supplied. [1][2]

Work was accepted for processing, but may not yet have completed. [1][2]

Successful but transformed information from an intermediary. [1][2]

Success with no response content; do not assume a JSON response body. [1][2]

Success asking a user agent to reset document view or input. [1][2]

Range request succeeded partially; inspect Content-Range and Range. [1][2]

WebDAV response reports separate statuses for several resources. [1][2]

WebDAV-specific deduplication information within a multistatus response. [1][2]

Delta-encoding extension indicating instance manipulation applied. [1][2]

More than one representation or resource choice is available. [1][2]

Permanent redirect; review Location and method semantics. [1][2]

Temporary redirect, historically allowing method changes on follow-up requests. [1][2]

Redirect client to retrieve a different URI, generally with GET. [1][2]

Conditional request validated cached representation; not a full new entity body. [1][2]

Deprecated redirect mechanism; do not build modern API logic around it. [1][2]

Temporary redirect that preserves the request method. [1][2]

Permanent redirect that preserves the request method. [1][2]

Multiple hops can cause latency or redirect loops. [1][2]

A 304 depends on conditional request headers. [1][2]

Request format or other client-side syntax is invalid; inspect body, query and headers. [1][2]

Client authentication is required or inadequate; check WWW-Authenticate. [1][2]

Reserved code with no standard universal payment workflow. [1][2]

Server understood request but refuses it; account and policy may prohibit access. [1][2]

Target resource or chosen route could not be found or is concealed. [1][2]

Route exists but does not allow this method; inspect Allow header. [1][2]

Server cannot produce an acceptable representation for requested negotiation. [1][2]

Authentication is required with an intermediary proxy. [1][2]

Server did not receive a complete request in its permitted time. [1][2]

Request conflicts with current resource state; inspect versions or concurrent updates. [1][2]

Resource is intentionally unavailable, generally indicating removal rather than transient absence. [1][2]

Server expects a valid Content-Length where required. [1][2]

Conditional request guard such as If-Match did not succeed. [1][2]

Request content exceeds server processing limits; check upload and reverse-proxy limits. [1][2]

Request target exceeds accepted size; shorten or move data into a body where appropriate. [1][2]

Content-Type or encoding is not supported by the endpoint. [1][2]

Requested byte range cannot be served from the representation. [1][2]

A request expectation in Expect header cannot be met. [1][2]

Connection reached a server that cannot authoritatively respond for target origin. [1][2]

Syntax is understood but instructions cannot be processed; inspect validation errors. [1][2]

WebDAV target is locked against the attempted change. [1][2]

WebDAV request depends on an operation that did not succeed. [1][2]

Server avoids processing replay-risky early-data request. [1][2]

Server requires a different protocol, with Upgrade guidance. [1][2]

Server requires a conditional write to prevent lost updates. [1][2]

Rate limit hit; obey Retry-After if provided and apply backoff. [1][2]

Reduce oversized cookies or other request headers. [1][2]

Target is unavailable due to a legal demand or restriction. [1][2]

Generic failure during processing; correlate logs with request identifier. [1][2]

Server lacks the requested capability, often an unrecognized method. [1][2]

Proxy or gateway got an invalid upstream response; inspect upstream health. [1][2]

Temporary overload or maintenance is possible; Retry-After may guide retry. [1][2]

Gateway waited too long for upstream; check service latency and network. [1][2]

Server rejects the protocol version used in request. [1][2]

Server configuration caused a negotiation loop for a resource. [1][2]

WebDAV server cannot store needed representation or state. [1][2]

WebDAV server encountered an infinite loop during processing. [1][2]

Network intermediary may demand portal authentication. [1][2]

Test the gateway-to-origin path, timeout and upstream logs. [1][2]

Retry only with appropriate credentials or permission changes. [1][2]

Decide whether the resource has permanently been removed. [1][2]

Check method semantics and idempotency keys before retrying writes. [1][2]