[Bug] Acquire token ( Refresh token ) not working

[vipins-optimus]

I have an angular project(version 5.2), and using ADAL service(adal-angular5). After login first time, no error message comes, but when i refresh the browser, the error message comes as =>

Here is my interceptor code:

    constructor(private adalService: Adal5Service, private loaderService: LoaderService) { }

    addToken(req: HttpRequest<any>, token: string): HttpRequest<any> {
        return req.clone({
            url: environment.apiUrl + req.url,
            headers: req.headers
                .set('Content-Type', 'application/json')
                .set('Authorization', 'Bearer ' + token)
        });
    }

    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        this.adalService.acquireToken(environment.adalConfig.resource).subscribe();
        return next.handle(this.addToken(req, this.adalService.userInfo.token))
        .finally(() => this.loaderService.display(false));
    }