angular: Uncaught Error: Can't resolve all parameters for ...

You are missing an @Injectable() annotation on your ApiService. Support requests like these should live on StackOverflow not GitHub.

After 1 day on this I realized I had removed some polyfills I didn’t think I need. This is what I was missing:

 import 'core-js/es7/reflect';

Any thoughts on adding actual useful error messages that detect common Angular pitfalls like Vue does?

@benelliott Thank you for the hint. I’m sorry but I thought it was an issue in angular. I’ve done a lot of research on StackOverflow and on Internet in general, but didn’t find a solution.,…So I thought it was an angular issue…Closing it. Thank you and sorry again

After strugling for 1 hour on this, finally, thanks to @odolha , it appears I also had removed core-js/es7/reflect. Adding it again solve the problem !

Error: Can’t resolve all parameters for Router: (?, ?, ?, ?, ?, ?, ?, ?).

I have this error in my angular4 app testing

I was missing the @ in front of Injectable(). If you get an error in an extremely simple scenario and you find nothing on the web about it, then most probably it’s too simple/stupid to be documented. Found that on my own too many times now.

For the record, I’ve just lost a full day on this error… 😭

In main.ts, polyfills MUST ABSOLUTELY be loaded first. Check

import './polyfills.ts';

is your first line.

I faced the same issue and resolved in my case, I had missed @Injectable decorator in server.service.ts file

Just in case you need to see how looks my app.component.ts

import { Component, OnInit } from '@angular/core';
import { TestService } from './services/test.service';

@Component({
  selector: 'tst-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
  title = 'tst';
  races: Array<any>;

  constructor(private testService: TestService ) {}

  ngOnInit() {
    this.races = this.testService.list();
  }
}

@dongdongmao i had this issue many times when: 1.) forgot to use the @Injectable() in the service and 2.) when some of my angular services, modules, etc exported as export default const foo = 123 instead of export const foo = 123. The key point here is not using default as export.

This can also happen when your component extends another one and you forgot to call the super() in your constructor.

can occur also with circular dependencies (exported helper structures between files).

This can also happen when your component extends another one and you forgot to call the super() in your constructor.

This was the case for me, extended a class and did not define the constructor at all. Thanks!

@odolha this was my issue as well. Glad you spent the day and not me (only took about 20 min to find your post)

The reason I had removed the polyfill was because there is a comment in the polyfill.ts for that polyfill that says this: // Used for reflect-metadata in JIT. If you use AOT (and only Angular decorators), you can remove.

So, I was doing some optimizing for my aot deployment and got rid of it… completely forgetting that local development (using ng-serve) is still using JIT 😦

So, thank you sir…

I had this error message also … what resolved it for me was importing Services from the same Module with relative paths rather than using a barrel.

I finally found out what was wrong in my case as well. Given the error: Can't resolve all parameters for PageApiService in .../services/pageService.ts: ([object Object], ?)

It looks like it is actually telling me that the place where the question mark is, has an issue. In my case I had HttpClient and a string in the url. In the hope to eventually use it within a provider and provide that string. but it looks like this not not allowed any more?

My service was:

@Injectable()
export class PageApiService<T> {
    private baseUrl: string;

    constructor(private http: HttpClient, private url: string) {
        this.baseUrl = window.location.protocol + '//' + window.location.host + "/api/";
    }

Using inside a module like so:

    providers: [{
        provide: 'ContactPlanPageService', useFactory: http => new PageApiService<ContactPlanModel>(http, 'contactplan/page'),
        deps: [HttpClient]
    }],

It did work though…yet it does give me a warning now that it will be an error in a later version…

Okay , so I have finally decoded the error . Note that if there is any unknown import statement in any component , the entire angular app crashes , so make a note of it . I resolved this error after thinking much. Hope it helps Cajetan Rodrigues

src\app\ordini\ordini.component.ts -> src\app\shared\ordini.service.ts -> src\app\ordini\ordini.component.t

Its clear that you are trying to inject the ordine service in the ordine component and ordine component in service. That is not possible. to instantiate the component you need the service and to instantiate the service you need the component. Please read about the dependency injection pattern.

if you have an index.ts to export your services, check the order of exports. that helped me.

In my case I was simply injecting in the constructor the Router service without using it. After deleting this, everything works fine.

I got this error when upgrading an app from angular2 to angular5. In addition to upgrading the CLI and the dependencies and devDependencies in the package.json, I had to update the old /tsconfig.json, and /angular-cli.json, to the new /tsconfig.json, src/tsconfig.app.json, tsconfig.spec.json, and /.angular-cli.json, and then calling

rm -rf node_modules/
npm i