使用rxJava2和改造的UndeliverableException

Question

There is an exception that is repeatedly showing up on Crashlytics(Fabric) for my app. I use rxjava2 with retrofit to make my http calls.

This is all that is there in the logs on crashlytics(below). Would be grateful for any help /insights.

Fatal Exception: io.reactivex.exceptions.UndeliverableException: retrofit2.adapter.rxjava2.HttpException: HTTP 404 
   at io.reactivex.plugins.RxJavaPlugins.onError(RxJavaPlugins.java:349)
   at io.reactivex.internal.operators.single.SingleZipArray$ZipCoordinator.innerError(SingleZipArray.java:141)
   at io.reactivex.internal.operators.single.SingleZipArray$ZipSingleObserver.onError(SingleZipArray.java:177)
   at io.reactivex.internal.operators.single.SingleDoOnError$DoOnError.onError(SingleDoOnError.java:63)
   at io.reactivex.internal.operators.single.SingleDoOnSuccess$DoOnSuccess.onError(SingleDoOnSuccess.java:64)
   at io.reactivex.internal.operators.single.SingleSubscribeOn$SubscribeOnObserver.onError(SingleSubscribeOn.java:73)
   at io.reactivex.internal.operators.observable.ObservableSingleSingle$SingleElementObserver.onError(ObservableSingleSingle.java:95)
   at retrofit2.adapter.rxjava2.BodyObservable$BodyObserver.onNext(BodyObservable.java:56)
   at retrofit2.adapter.rxjava2.BodyObservable$BodyObserver.onNext(BodyObservable.java:37)
   at retrofit2.adapter.rxjava2.CallExecuteObservable.subscribeActual(CallExecuteObservable.java:43)
   at io.reactivex.Observable.subscribe(Observable.java:10842)
   at retrofit2.adapter.rxjava2.BodyObservable.subscribeActual(BodyObservable.java:34)
   at io.reactivex.Observable.subscribe(Observable.java:10842)
   at io.reactivex.internal.operators.observable.ObservableSingleSingle.subscribeActual(ObservableSingleSingle.java:35)
   at io.reactivex.Single.subscribe(Single.java:2703)
   at io.reactivex.internal.operators.single.SingleSubscribeOn$SubscribeOnObserver.run(SingleSubscribeOn.java:89)
   at io.reactivex.Scheduler$DisposeTask.run(Scheduler.java:452)
   at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:61)
   at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:52)
   at java.util.concurrent.FutureTask.run(FutureTask.java:237)
   at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:152)
   at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:265)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
   at java.lang.Thread.run(Thread.java:818)
Caused by retrofit2.adapter.rxjava2.HttpException: HTTP 404 
   at retrofit2.adapter.rxjava2.BodyObservable$BodyObserver.onNext(BodyObservable.java:54)
   at retrofit2.adapter.rxjava2.BodyObservable$BodyObserver.onNext(BodyObservable.java:37)
   at retrofit2.adapter.rxjava2.CallExecuteObservable.subscribeActual(CallExecuteObservable.java:43)
   at io.reactivex.Observable.subscribe(Observable.java:10842)
   at retrofit2.adapter.rxjava2.BodyObservable.subscribeActual(BodyObservable.java:34)
   at io.reactivex.Observable.subscribe(Observable.java:10842)
   at io.reactivex.internal.operators.observable.ObservableSingleSingle.subscribeActual(ObservableSingleSingle.java:35)
   at io.reactivex.Single.subscribe(Single.java:2703)
   at io.reactivex.internal.operators.single.SingleSubscribeOn$SubscribeOnObserver.run(SingleSubscribeOn.java:89)
   at io.reactivex.Scheduler$DisposeTask.run(Scheduler.java:452)
   at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:61)
   at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:52)
   at java.util.concurrent.FutureTask.run(FutureTask.java:237)
   at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:152)
   at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:265)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
   at java.lang.Thread.run(Thread.java:818)

Answer 1

If your not giving the subscriber or th Observer the throwable lambda .. Rxjava has no way to catch those exceptions. so the simple solution is whenever subscribing on Observable or other Rxjava types overrride the onError() method and handle them depending on the situation.

compositeDisposable.add(Observable.just("start")
        .doOnNext(ignored -> loadingIndicator.onNext(true))
        .flatMap(ignored -> repository.getAndroidDev())
        .subscribe(posts::onNext, throwable -> Timber.e(throwable))); //second lambda is the solution, at lease you can log the errors, if you're not willing to handle them