Retry HTTP requests in angular 6

There are several errors in your code:

1. You are shadowing error variable - first it's an error stream and then it's an error object.
2. Using observableThrowError with delay has no effect. Error will bypass every operator except those dealing with error.
3. You are mixing "pipe(operator())" style operators and prototype style operators .operator().

I have suggested some changes:

.handle(customReq).pipe(
    tap((ev: HttpEvent<any>) => {
        if (ev instanceof HttpResponse) {
            console.log('###processing response', ev, this.location);
        }
    }),
    retryWhen(errors => errors
        .pipe(
            concatMap((error, count) => {
                if (count < 5 && (error.status == 400 || error.status == 0)) {
                    return Observable.of(error.status);
                }

                return observableThrowError(error);
            }),
            delay(1000)
        )
    ),

Main change is tracking error count through second argument of concatMap instead of using take opeator which is mainly useful for unsubscribing the observable and I think you want throw an error instead.