Error map

501 HTTP 501 Not Implemented

HTTP · layer 2, Network

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Centre: this error. First ring: errors it is linked with (3). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.

2 · Network 4 · Application & API
501 — HTTP 501 Not Implemented (HTTP)501500 — HTTP 500 Internal Server Error (HTTP)500505 — HTTP 505 HTTP Version Not Supported (HTTP)505405 — HTTP 405 Method Not Allowed (HTTP)405404 — HTTP 404 Not Found (HTTP)404502 — HTTP 502 Bad Gateway (HTTP)502503 — HTTP 503 Service Unavailable (HTTP)503400 — HTTP 400 Bad Request (HTTP)400100 — HTTP 100 Continue (HTTP)100103 — HTTP 103 Early Hints (HTTP)103403 — HTTP 403 Forbidden (HTTP)403CORS — CORS Error: No 'Access-Control-Allow-Origin' header is present (API)CORSWhitelabel Error Page — Whitelabel Error Page — This application has no explicit mapping for /error (Java)Whitelabel Error Pa…

Directly related (3)

500HTTP

HTTP 500 Internal Server Error

The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.

505HTTP

HTTP 505 HTTP Version Not Supported

The server doesn’t support the HTTP protocol version used in the request.

405HTTP

HTTP 405 Method Not Allowed

The URL exists, but it doesn’t accept the HTTP method you used (e.g. POST to a GET-only route).

Two steps away (9)

404HTTP

HTTP 404 Not Found

The server can’t find anything at the requested URL.

502HTTP

HTTP 502 Bad Gateway

A proxy or gateway (Nginx, load balancer, CDN) got an invalid response — or no response — from the upstream server behind it.

503HTTP

HTTP 503 Service Unavailable

The server is temporarily unable to handle the request — overloaded, in maintenance, or has no healthy backends.

400HTTP

HTTP 400 Bad Request

The server could not understand the request because its syntax, headers or body are malformed or invalid.

100HTTP

HTTP 100 Continue

An interim response telling the client to go ahead and send the request body — normal when the client sent Expect: 100-continue.

103HTTP

HTTP 103 Early Hints

An interim response that sends Link headers early so the browser can preload CSS, fonts or scripts while the server is still buil…

403HTTP

HTTP 403 Forbidden

The server understood the request but refuses to authorize it — you (or the server process) are not allowed to access this resour…

CORSAPI

CORS Error: No 'Access-Control-Allow-Origin' header is present

The browser blocked a cross-origin request because the server’s response didn’t include the CORS headers allowing your site’s ori…

Whitelabel Error PageJava

Whitelabel Error Page — This application has no explicit mapping for /error

Spring Boot’s default error page — the request hit no controller mapping (404) or a controller threw (500).

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