相关疑难解决方法(0)

我正在将我的Angular2应用程序从2.0.0升级到2.3.0,我遇到了以下错误.任何想法为什么？我看到了另一篇文章(Angular 2.0.1 Router EmptyError:序列中没有元素),但在尝试之后,问题仍然存在.是什么导致这个错误？

Error: Uncaught (in promise): EmptyError: no elements in sequence
Error: no elements in sequence
    at EmptyError.ZoneAwareError (zone.js:672)
    at new EmptyError (EmptyError.ts:13)
    at FirstSubscriber._complete (first.ts:161)
    at FirstSubscriber.Subscriber.complete (Subscriber.ts:122)
    at Subject._subscribe (Subject.ts:109)
    at Subject.Observable.subscribe (Observable.ts:98)
    at Observable._subscribe (Observable.ts:158)
    at Observable.subscribe (Observable.ts:98)
    at Observable._subscribe (Observable.ts:158)
    at FirstOperator.call (first.ts:82)
    at Observable.subscribe (Observable.ts:96)
    at Object.subscribeToResult (subscribeToResult.ts:32)
    at MergeAllSubscriber._next (mergeAll.ts:82)
    at MergeAllSubscriber.Subscriber.next (Subscriber.ts:95)
    at MapSubscriber._next (map.ts:80)
    at resolvePromise (zone.js:475) [angular]
    at resolvePromise (zone.js:460) [angular]
    at /libs/zone.js/dist/zone.js:509:17 [angular]
    at …