Error map
Whitelabel Error Page Whitelabel Error Page — This application has no explicit mapping for /error
Java · layer 4, Application & API
Centre: this error. First ring: errors it is linked with (12). 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.
Directly related (12)
HTTP 500 Internal Server Error
The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.
HTTP 404 Not Found
The server can’t find anything at the requested URL.
Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
Spring Boot found JDBC/JPA on the classpath but no database URL.
MethodArgumentNotValidException: Validation failed for argument [0]
Bean Validation (@Valid with @NotNull, @Email, @Size…) rejected the request body.
Cloudflare Error 1019: Compute server error (Workers)
A Cloudflare Worker routed the request to a loop or hit an internal compute error.
UnsatisfiedDependencyException / NoSuchBeanDefinitionException: No qualifying bean of type 'X' available
Spring couldn’t find (or choose) a bean to inject.
HttpMessageNotReadableException: JSON parse error / Required request body is missing
Spring couldn’t read the request body into your @RequestBody object.
Web server failed to start. Port 8080 was already in use.
Spring Boot couldn’t bind its embedded server port because another process uses it.
TypeError: Missing parameter name at 1 (path-to-regexp)
An Express 5 (path-to-regexp v8) route uses old wildcard syntax like '*' or '/:id?'.
API Error: Cannot GET /api/... / No route matches / The route could not be found
The server has no route for this URL and HTTP method combination — the endpoint path, API version prefix or method is wrong.
connect: Network is unreachable (ENETUNREACH)
The host has no route to the destination network — no default gateway, interface down, or trying IPv6 without IPv6 connectivity.
The dependencies of some of the beans in the application context form a cycle
Two or more Spring beans depend on each other through constructors, and Spring Boot 2.6+ forbids cycles by default.
Two steps away (32)
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.
HTTP 503 Service Unavailable
The server is temporarily unable to handle the request — overloaded, in maintenance, or has no healthy backends.
SyntaxError: Unexpected token < in JSON at position 0
`JSON.parse()` / `response.json()` received something that isn’t JSON — very often an HTML error page.
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…
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).
HTTP 410 Gone
The resource used to exist but was intentionally and permanently removed, with no forwarding address.
OAuth Error: redirect_uri_mismatch
The redirect URI in your OAuth request doesn’t exactly match one registered for the client in the provider’s console.
hint: You have divergent branches and need to specify how to reconcile them.
Git 2.27+ asks you to choose merge, rebase or fast-forward-only when local and remote both have new commits.
warning: in the working copy of 'x', LF will be replaced by CRLF the next time Git touches it
Git’s line-ending conversion (core.autocrlf) will change line endings in your working copy.
HTTP 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
HTTP 422 Unprocessable Content
The request is well-formed, but the data fails validation (e.g. invalid email, missing required field).
java.lang.NumberFormatException: For input string: "x"
A string couldn’t be parsed as a number — it’s empty, has spaces/commas, is too large, or isn’t numeric.
No routes matched location "/x"
React Router found no route definition for the current URL.
Error: NextRouter was not mounted.
next/router’s useRouter was used inside the App Router (app/ directory), which uses next/navigation instead.
Cloudflare Error 1025: Please check back later (Workers request limit)
The site’s Cloudflare Workers plan exceeded its daily request limit (free plan: 100,000 requests/day).
InvalidOperationException: Unable to resolve service for type 'X' while attempting to activate 'Y'
ASP.NET Core’s dependency injection container can’t build Y because one of its constructor dependencies (X) was never registered.
Angular: NullInjectorError: No provider for X!
Angular’s dependency injection couldn’t find a provider for a service/token the component needs.
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `java.util.ArrayList` from Object value
Jackson found JSON whose shape doesn’t match the target Java type (object vs array, string vs number, missing constructor).
com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "x", not marked as ignorable
The JSON contains a field your Java class doesn’t have, and Jackson is configured to fail on unknown properties.
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class X and no properties discovered
Jackson can’t serialize the class — it has no public getters/fields, or it’s a Hibernate proxy, or Java 8 date types without the…
Error: listen EADDRINUSE: address already in use :::3000
Another process is already listening on that port.
Docker: Bind for 0.0.0.0:80 failed: port is already allocated
Another container or host process already publishes that host port.
LOG: could not bind IPv4 address "0.0.0.0": Address already in use — Is another postmaster already running on port 5432?
Another process (often a second PostgreSQL install or a container) already listens on 5432.
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
An Express/Node handler tried to send a second response (or set headers) after one was already sent.
Express: req.body is undefined / {} (body parser missing)
Express didn’t parse the request body because no body-parsing middleware matched the request’s Content-Type.
TypeError: Router.use() requires a middleware function but got a Object
app.use()/router.use() received an object instead of a function — usually a router module that wasn’t exported.
URIError: URI malformed
decodeURIComponent/decodeURI received an invalid percent-encoded sequence.
API Error: Invalid or unsupported API version
The API version you requested — in the URL, a header or the SDK config — doesn’t exist or has been retired.
AmbiguousMatchException: The request matched multiple endpoints. Matches: X, Y
Two controller actions or minimal API endpoints have the same route and HTTP method.
Error: socket hang up / read ECONNRESET
The other side closed the TCP connection abruptly while your client was still using it.
Error: getaddrinfo ENOTFOUND host / Name or service not known
DNS lookup for the hostname failed — the name is wrong, doesn’t exist, or this machine can’t resolve it.
ssh: connect to host x port 22: Connection refused
The server answered, but nothing is listening on the SSH port — sshd isn’t running, it uses another port, or a firewall actively…
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