TypeError: You provided an invalid object where a stream was expected. You can provide an Observable, Promise, Array, or Iterable

In my case the error occurred only during e2e tests. It was caused by throwError in my AuthenticationInterceptor.

I imported it from a wrong source because I used WebStorm's import feature. I am using RxJS 6.2.

Wrong:

import { throwError } from 'rxjs/internal/observable/throwError';

Correct:

import { throwError } from 'rxjs';

Here the full code of the interceptor:

import { Injectable } from '@angular/core';import { HttpErrorResponse, HttpEvent, HttpHandler, HttpInterceptor, HttpRequest } from '@angular/common/http';import { Observable, throwError } from 'rxjs';import { catchError } from 'rxjs/operators';@Injectable()export class AuthenticationInterceptor implements HttpInterceptor {  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {    const reqWithCredentials = req.clone({withCredentials: true});    return next.handle(reqWithCredentials)     .pipe(        catchError(error => {          if (error.status === 401 || error.status === 403) {            // handle error          }          return throwError(error);        })     );  }}

In your example code, you have your map operator receiving two callbacks, when it should only be receiving one. You can move your error handling code to your catch callback.

checkLogin():Observable<boolean>{    return this.service.getData()                       .map(response => {                            this.data = response;                                                      this.checkservice=true;                          return true;                       })                       .catch(error => {                          this.router.navigate(['newpage']);                          console.log(error);                          return Observable.throw(error);                       })   }

You'll need to also import the catch and throw operators.

import 'rxjs/add/operator/catch';import 'rxjs/add/observable/throw';

EDIT: Note that by returning Observable.throwin your catch handler, you won't actually capture the error - it will still surface to the console.

If your function is expecting to return a boolean, just do this:

1. Import:

import { of, Observable } from 'rxjs';import { map, catchError } from 'rxjs/operators';

2. Then

checkLogin(): Observable<boolean> {  return this.service.getData()    .pipe(      map(response => {        this.data = response;        this.checkservice = true;        return true;      }),      catchError(error => {        this.router.navigate(['newpage']);        console.log(error);        return of(false);      }))}