angular

NullInjectorError — missing provider

NullInjectorError: No provider for (\w+)

Fixes

1.Add the service to the `providers` array of the module or component that needs it
2.Use `@Injectable({ providedIn: 'root' })` on the service class for app-wide singleton
3.If using a lazy-loaded module, ensure the service is provided in that module or root

dependency-injectionproviders

Related Errors

ExpressionChangedAfterItHasBeenCheckedError (NG0100)

NG0100.*Expression has changed after it was checked

•Move the value change to ngAfterViewInit with a ChangeDetectorRef.detectChanges() call
•Use setTimeout(() => { ... }) to defer the change to the next cycle

Circular dependency in DI (NG0200)

NG0200.*Circular dependency in DI detected

•Break the cycle by injecting one service lazily with `@Inject(forwardRef(() => ServiceName))`
•Extract shared logic into a third service that both services depend on

Can't bind to property — not a known property (NG0303)

NG0303.*Can't bind to '.+' since it isn't a known property

•Import the module that declares the directive/component (e.g., FormsModule for ngModel, ReactiveFormsModule for formControl)
•Check for typos in the property name or directive selector