Error map
NullInjectorError Angular: NullInjectorError: No provider for X!
Angular · layer 1, On your device
Centre: this error. First ring: errors it is linked with (11). 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 (11)
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.
UnsatisfiedDependencyException / NoSuchBeanDefinitionException: No qualifying bean of type 'X' available
Spring couldn’t find (or choose) a bean to inject.
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.
Angular: NG0100: ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked
A template value changed during the same change-detection cycle in which Angular already checked it (dev-mode only error).
Angular: NG8002: Can't bind to 'ngModel' since it isn't a known property of 'input'
The template uses a property binding that no imported directive provides — for ngModel, FormsModule isn’t imported.
Angular: NG8001: 'app-item' is not a known element — verify that it is included in the component's imports
The template uses a tag Angular does not recognise as a component — it was never imported (standalone) or declared/exported (NgMo…
Angular: NG0203: inject() must be called from an injection context such as a constructor, a factory function, a field initializer or a function used with runInInjectionContext
`inject()` was called somewhere Angular is not constructing a class — for example inside a method, a callback or after an `await`.
Angular: NullInjectorError: No provider for HttpClient! — provideHttpClient() missing
A service or component injects `HttpClient`, but HTTP support was never added to the app's providers.
Angular: NG0200: Circular dependency in DI detected for X
Two or more services inject each other (directly or through a chain), so Angular cannot create any of them first.
Angular: NG0201: No provider for X found in NodeInjector
A component or directive asked for a service no injector in its tree provides.
Angular: NullInjectorError: No provider for ActivatedRoute! (also Router) — usually a unit test
A component injects `ActivatedRoute` or `Router`, but no router providers exist in the injector — typical in unit tests or when t…
Two steps away (27)
System.NullReferenceException: Object reference not set to an instance of an object
Code dereferenced a variable that is `null` — the .NET equivalent of Java’s NullPointerException.
HTTP Error 500.30 - ASP.NET Core app failed to start
IIS/Azure’s ASP.NET Core Module launched your app but it crashed during startup.
JsonException: A possible object cycle was detected
System.Text.Json found a reference loop (e.g. Order → Customer → Orders → …) while serialising, usually from EF Core navigation p…
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.
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.
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).
HttpMessageNotReadableException: JSON parse error / Required request body is missing
Spring couldn’t read the request body into your @RequestBody object.
MethodArgumentNotValidException: Validation failed for argument [0]
Bean Validation (@Valid with @NotNull, @Email, @Size…) rejected the request body.
TS2564: Property 'x' has no initializer and is not definitely assigned in the constructor
With strictPropertyInitialization on, a class property declared without ? or a default isn’t set in the constructor.
Angular: Error: Cannot find control with name: 'email' (reactive forms)
A `formControlName` points at a control that does not exist in the bound `FormGroup`.
Angular SSR: NG0500: During hydration Angular expected <div> but found <span> (NG0501, NG0502)
The HTML rendered on the server does not match what the browser's Angular app tried to render, so hydration failed and the page w…
Warning: A component is changing an uncontrolled input to be controlled
An input’s `value` started as `undefined` (uncontrolled) and later became a defined value (controlled), or vice versa.
django.template.exceptions.TemplateDoesNotExist: app/page.html
Django searched all template directories and couldn’t find that template.
Contact Form 7: There was an error trying to send your message. Please try again later.
The form submitted, but wp_mail() failed to send — the server can’t send mail or the mail settings are wrong.
Angular: NG8003: No directive found with exportAs 'ngForm' (template reference variable)
A template reference such as `#f="ngForm"` points at a directive Angular cannot find on that element — the module that provides i…
Angular: NG8004: No pipe found with name 'async' / 'date' / 'translate' — pipe not imported
The template uses a pipe Angular does not know — it is not imported into the component (standalone) or its module.
Angular: NG8103: The *ngIf directive was used, but neither the NgIf directive nor the CommonModule was imported
A standalone component uses `*ngIf`, `*ngFor` or `ngClass` without importing the directive — or should migrate to the built-in `@…
Angular: NG0600: Writing to signals is not allowed in a computed or an effect by default
A `computed()` (or, by default, an `effect()`) tried to call `.set()` or `.update()` on a signal — that creates hidden update loo…
Angular CLI: Schema validation failed with the following errors: Data path "" must NOT have additional properties(xyz)
`angular.json` (or an option you passed to a builder) contains a property the schema does not allow — a typo, an option removed i…
Angular: NG0950: Input is required but no value is available yet (input.required / viewChild.required)
A required signal input or query was read before Angular set it — in the constructor or too early in the lifecycle.
Angular: HttpErrorResponse — Http failure response for (unknown url): 0 Unknown Error (status 0)
`HttpClient` got no HTTP response at all: the request was blocked (CORS), failed at network level, or the server is unreachable —…
Angular: Http failure response for http://…/api/x: 404 Not Found (HttpErrorResponse)
The API answered 404 — the URL is wrong (base URL, path or id), or the proxy/rewrite does not forward the request.
Angular: Http failure during parsing for http://…: SyntaxError: Unexpected token '<' (response is not JSON)
The request succeeded (status 200) but the body could not be parsed as the expected type — usually HTML or plain text instead of…
Angular build: Error: bundle initial exceeded maximum budget. Budget 1.00 MB was not met by 120.00 kB with a total of 1.12 MB
The production build is larger than the size limits (budgets) in angular.json, and the build is configured to fail.
Angular: NG04002: Cannot match any routes. URL Segment: 'x'
The router found no route for the URL you navigated to — missing route, wrong path, or an unloaded lazy route.
Angular: NG04014: Invalid configuration of route 'x': one of the following must be provided: component, loadComponent, redirectTo, children or loadChildren
A route object has a path but nothing for the router to render or load.
Angular (production): Cannot GET /dashboard — 404 when refreshing or opening a deep link
The web server only knows `index.html`; a direct request to `/dashboard` is not a file, so it returns 404 instead of letting Angu…
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