Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstalliTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Angular’s NG0204 means it could not resolve a dependency while constructing a class. Start with the exact error text: in Can't resolve all parameters for X: (?, ?, ?), each question mark marks a constructor parameter Angular could not resolve. Check the corresponding parameter for missing injectable metadata, a missing runtime token, an unavailable provider, or a different InjectionToken instance at the provider and injection sites.
What Angular NG0204 means
NG0204 is Angular’s “Invalid Injection Token” error. It occurs when Angular cannot resolve a dependency for a class during dependency injection. The reported class is the one Angular was trying to construct; inspect its constructor and trace backward through the stack trace to find what triggered that construction.
The wording narrows the search. In Can't resolve all parameters for X: (?, ?, ?), match each ? to the constructor argument in that position. If the message instead says Token X is missing a ɵprov definition, Angular is saying the token lacks a provider definition. Register a provider for it, or give the token a suitable default factory.
Diagnose the failing dependency
-
Map the error to a constructor parameter
Find the class named in the error and inspect the parameters in its constructor in order. Focus first on each position marked with
?; those are the unresolved arguments.#1 Best Overall
-
Check the class’s injectable metadata
If Angular needs to construct a class that has constructor dependencies, ensure it has the appropriate
@Injectable()metadata. A class with dependencies but without the required injectable metadata can prevent Angular from resolving its constructor. -
Confirm the parameter has a runtime token
Angular needs a runtime value it can use as a dependency token. TypeScript interfaces and other type-only forms disappear after compilation, so they cannot identify a dependency on their own. For interface-shaped values, functions, arrays, and parameterized types, define an
InjectionTokenand use it to provide and inject the value. -
Verify that a provider is available
A valid token must also have a provider available to the consumer unless it is configured with an appropriate factory or otherwise provided automatically. Check whether the provider is registered in a scope visible to the class that requests it. Angular supports automatic provision through
@Injectableor a token factory, as well as manual registration in provider arrays.Special offer. See more information about Outbyte and uninstall instructions. Please review EULA and Privacy policy. -
Check that provider and consumer use the same token object
An
InjectionTokendescription is for debugging; Angular uses the token object’s identity. Define and export a token once in a shared file, then import that same instance wherever it is provided or injected. Creating two tokens with identical descriptions still creates two distinct tokens.
Use an InjectionToken for values without a runtime type
For interface-shaped configuration or another value without a reified runtime representation, define one shared token and use it at both ends. The generic type parameter provides TypeScript type information; the token object provides the runtime identity Angular needs.
import { InjectionToken } from '@angular/core';
export interface AppConfig {
apiUrl: string;
}
export const APP_CONFIG = new InjectionToken<AppConfig>('app.config');Register a provider for that token in a scope available to the consumer. Choose the provider strategy based on what the dependency represents:
useValuesupplies a fixed value, such as a configuration object.useClasstells Angular which class to construct.useFactorycreates the dependency through a factory function.useExistingaliases another provider.
At the injection site, request the same exported token—for example, with @Inject(APP_CONFIG) on a constructor parameter. Do not create a second InjectionToken with the same description for the provider or consumer.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Why common attempted fixes may not work
Adding @Optional() does not create a token
@Optional() can make an otherwise valid dependency optional when no provider is found. It does not give an interface a runtime identity, register a provider, or make two separately created tokens equivalent.
Registering the provider under a different token does not satisfy the request
Provider and consumer must refer to the same token object. Matching text in their descriptions is not enough.
Calling inject() later is a different problem
Angular permits inject() during construction, field initialization, and provider or token factory execution. Calling it later, such as from a lifecycle hook, is outside the injection context and is associated with NG0203, not NG0204. Move the call into a supported context when the reported code is NG0203.
Distinguish NG0204 from related Angular DI errors
- NG0204 — Invalid Injection Token: Angular cannot resolve a dependency while constructing a class. Inspect the constructor, runtime token, provider, and token identity.
- NG2003 — Missing Token: Angular has no runtime token for a constructor parameter, often because the parameter uses a primitive type. Use an appropriate runtime token, commonly an
InjectionTokenfor a value that has no runtime class representation. - NG0203 — Injection Context:
inject()was called outside a supported injection context. Fix where the call occurs rather than changing provider registration unless a separate provider problem is also present.
Use the code Angular actually reports to choose the correction; these errors can appear related, but they identify different failure conditions.
Recommended Free Tools
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
