NullPointerException when showing Android Modal

[idris]

Description

We are getting a NullPointerException sometimes upon trying to show a modal (see "Reproduction" section for details).

Stack Trace:

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.facebook.react.uimanager.ReactShadowNode.setStyleWidth(float)' on a null object reference
	at com.facebook.react.uimanager.UIImplementation.updateNodeSize(UIImplementation.java:151)
	at com.facebook.react.uimanager.UIManagerModule.updateNodeSize(UIManagerModule.java:213)
	at com.facebook.react.views.modal.ReactModalHostView$DialogRootViewGroup$1.run(ReactModalHostView.java:301)
	at android.os.Handler.handleCallback(Handler.java:739)
	at android.os.Handler.dispatchMessage(Handler.java:95)
	at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31)
	at android.os.Looper.loop(Looper.java:148)
	at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:196)
	at java.lang.Thread.run(Thread.java:818)

It sounds like this commit may be related, and may have fixed a similar issue: 922cd6d
From that commit message:

In some cases, the size of the content view changes before we add views to the
Modal. That means that the size of that view will not be set through the
onSizeChanged method. This can result in some apps apparently freezing,
since the dialog is created, but there are no actual views in it.

The part about "dialog is created, but there are no actual views in it" makes me feel it's related, because the NullPointerException happens here: https://github.com/facebook/react-native/blob/v0.36.0/ReactAndroid/src/main/java/com/facebook/react/views/modal/ReactModalHostView.java#L301-L302
So apparently getChildAt(0).getId() returns an ID that is unavailable by the time setStyleWidth is called.

Reproduction

Unfortunately, it's a tough case to reproduce. Even in our app it only happens about half the time. We have one modal show first, and when the user clicks "OK" on that one, we show another "saving" modal, then when saving is complete we remove the modal. It seems in between the user clicking "OK" and the "saving" modal displaying, we get a crash (about half the time).

Additional Information

• React Native version: v0.36.0
• Platform: Android (tested on Nexus 5)
• Operating System: Android (Tried genymotion, but can only reproduce on a real device)

[charpeni]

@facebook-github-bot label Android

[akzhou]

I have the same question on React Native version: v0.36.1

[kruczy]

Hi,
I have a similar issue that happens only when closing a modal (but not always), the error is in a different place in the code but it seems it is related: https://github.com/facebook/react-native/blob/master/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java#L151

hope this helps with solving the problem

[idris]

Looks like @Proberts has a way to reproduce this: #10845 (comment)

[fermuch]

Same issue in RN 0.39.0. It happens randomly, but seems to be triggered by onLayout on the root component.

[grahamtallen]

+1

[mwbres]

I only experience this crash on QA or prod builds for some reason. But yeah, this still needs a solution(v0.39).

[mwbres]

My company needed a fix for this, as this crash was happening in production and it was vital we fixed it, but we were unable to come up with a good method of testing and fixing this issue. We managed to "fix" the issue by ripping out the Modal component from our code. In our case, Modal was used to show a loading indicator.

We definitely need a true fix for this issue though.

[JakeRawr]

+1, This happens for me even if visible = { false }

[butchmarshall]

I get this crash randomly while using react-native-loading-spinner-overlay

[gsaandy]

any updates on this?

[fermuch]

@gsaandy after using a custom version compiled from master, the problem is gone for me.
I'm using react-native-router-flux for navigation.

[kelvinaliyanto]

Any workaround for this now?

[jlo1]

Seems fixed in latest 0.44.0 release (5873a22)

[charpeni]

Then let's close this, if it happens again please open a new issue.

[charpeni]

@facebook-github-bot close

[facebook-github-bot]

@charpeni tells me to close this issue. If you think it should still be opened let us know why.

[weimengxi]

@JakeRawr I've met this problem, too. visible = { false } leads to crash in ios .