Error map
400 HTTP 400 Bad Request
HTTP · layer 2, Network
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 422 Unprocessable Content
The request is well-formed, but the data fails validation (e.g. invalid email, missing required field).
OAuth 2.0 Error: invalid_grant
The authorization code, refresh token or credentials sent to the token endpoint are invalid, expired, already used or were issued…
django.core.exceptions.DisallowedHost: Invalid HTTP_HOST header: 'x'. You may need to add 'x' to ALLOWED_HOSTS.
The request’s Host header isn’t listed in Django’s ALLOWED_HOSTS.
HTTP 401 Unauthorized
The request has no valid authentication credentials — you need to log in or send a valid token.
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.
GraphQL: Cannot query field "x" on type "Y"
The query asks for a field that doesn’t exist in the server’s schema (or isn’t available on that type).
MethodArgumentNotValidException: Validation failed for argument [0]
Bean Validation (@Valid with @NotNull, @Email, @Size…) rejected the request body.
Invalid Request
The API rejected the request because one or more parameters, headers, fields, or request values are invalid or malformed.
API Error: Malformed JSON in request body (entity.parse.failed / JSON parse error)
The server couldn’t parse the request body as JSON, so it rejected the request before looking at any field.
HTTP 411 Length Required
The server refuses a request with a body but no Content-Length header.
API Error: Invalid type — expected integer, received string
A request field has the wrong data type — a string where the API expects a number, a number where it expects a boolean, an object…
API Error: Invalid date format — expected ISO 8601 (YYYY-MM-DDTHH:mm:ssZ)
A date or timestamp in the request isn’t in the format the API expects — usually ISO 8601 with a time zone, or a Unix timestamp.
Two steps away (34)
HTTP 415 Unsupported Media Type
The server refuses the request because the body’s Content-Type isn’t one it accepts.
HTTP 409 Conflict
The request conflicts with the current state of the resource — e.g. a duplicate or an edit based on an outdated version.
MySQL ERROR 1406: Data too long for column
The value is longer than the column allows (e.g. 300 characters into VARCHAR(255)), and strict mode rejects it instead of truncat…
Azure AD (Entra ID): AADSTS700016 Application not found in the directory
The client ID in your sign-in request doesn’t exist in the tenant you’re authenticating against.
JWT Expired / Invalid Token
The JSON Web Token sent with the request is expired, malformed or signed with a different key, so the API rejects it (usually wit…
OAuth 2.0 Error: invalid_client
The OAuth server couldn’t authenticate your application — wrong client ID/secret, wrong auth method, or the client doesn’t exist…
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.
Python was not found; run without arguments to install from the Microsoft Store
Windows ran the Microsoft Store “App execution alias” instead of a real Python installation.
django.db.utils.OperationalError: no such table: app_model
Django queried a table that hasn’t been created — migrations missing or not applied.
Kubernetes: ImagePullBackOff / ErrImagePull
The node can’t pull the container image — wrong name/tag, missing registry credentials, or registry unreachable.
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 407 Proxy Authentication Required
A proxy between you and the server requires credentials before it will forward your request.
Author identity unknown *** Please tell me who you are.
Git doesn’t know your name and email for 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.
error: gpg failed to sign the data — fatal: failed to write commit object
Commit signing is enabled but GPG couldn’t sign — no TTY for the passphrase, wrong key, or agent not running.
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…
HTTP 200 OK (but something is still wrong)
The request succeeded at the HTTP level — yet the page is blank, the data is wrong, or an error is hidden inside the response bod…
MySQL ERROR 1005 (HY000): Can't create table (errno: 150 "Foreign key constraint is incorrectly formed")
A foreign key definition is invalid — the referenced column’s type, index or charset doesn’t match.
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.
java.lang.IllegalArgumentException
A method rejected an argument value as invalid.
UnsatisfiedDependencyException / NoSuchBeanDefinitionException: No qualifying bean of type 'X' available
Spring couldn’t find (or choose) a bean to inject.
API Error: Invalid API Key / Incorrect API key provided
The API didn’t recognise the key sent with the request — it’s wrong, revoked, from another environment, or sent in the wrong plac…
SyntaxError: Unexpected token < in JSON at position 0
`JSON.parse()` / `response.json()` received something that isn’t JSON — very often an HTML error page.
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.
HTTP 413 Content Too Large (Request Entity Too Large)
The request body is bigger than the server is willing to accept — usually a file upload over the configured limit.
Refused to load the script because it violates the following Content Security Policy directive
The page’s Content-Security-Policy doesn’t allow that script, style, image or connection source.
Warning: session_start(): Session cannot be started after headers have already been sent
session_start() ran after output was sent, so PHP can’t set the session cookie.
MySQL ERROR 1048 (23000): Column 'x' cannot be null
An INSERT/UPDATE put NULL into a NOT NULL column.
MySQL ERROR 1264 (22003): Out of range value for column 'x' at row 1
A number is too large (or negative for UNSIGNED) for the column type.
MySQL ERROR 1292 (22007): Incorrect datetime value: 'x' for column 'y'
A string couldn’t be converted to DATE/DATETIME — wrong format, empty string, or a zero date in strict mode.
java.time.format.DateTimeParseException: Text '31/12/2024' could not be parsed at index 2
A java.time parse call got text that doesn’t match the expected format.
java.text.ParseException: Unparseable date: "x"
SimpleDateFormat couldn’t parse the string with its pattern.
RangeError: Invalid time value
A Date is invalid (NaN), and toISOString() or a formatting library couldn’t format it.
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