Angular 4: "Http failure response for (unknown URL): 0 Unknown Error"

Question

I am trying to consume an API URL. I am calling the API with the below code.

import {HttpClient, HttpClientModule, HttpParams} from "@angular/common/http";

@Injectable()
export class PropertyPrefService {

    constructor(private http: HttpClient,
                private configurationService:Configuration) {}

    public searchProjects(propFilter:string):any{
        let temp:any;
        const options = propFilter ?
        {
            params: new HttpParams().set('query', propFilter)
        } : {};

        return this.http.get<any>(this.configurationService.propertySystemApiUrl, options)
                    .subscribe((results:any) => {
                        console.log(results);
                    });
    }

In the Angular code I am not getting any response and am getting an error:

Http failure response for (unknown url): 0 Unknown Error".

However, when I make a request if I open up developer tools on Chrome, I see that the response is received from the server.

The URL is the "https://..." URL and not "http://...".

Answer 1

The problem is Angular Universal used Express, and the security validates the SSL certificate to the server; I used a self-signed SSL certificate.

The solution is to add NODE_TLS_REJECT_UNAUTHORIZED=0 to your environment to disable the SSL verification in Node.js. You should only set this in development; in production it is very risky.

Answer 2

Quoting Sander Elias on Google Groups:

"Error 0 is what you get when the request does not go out. Most common cause of this is that CORS is not configured correctly on the server. Let me rephrase that to: In 98% of the cases, this is a server side issue."

Answer 3

You are not in the same domain, same protocol, same port between backend and frontend.

Answer 4

Just in case anyone else stumbles on this, none of these solutions worked for me. What worked for me was turning off uBlock Origin. It was blocking any url that had the word "ad" in it for obvious reasons.