Did something change on the builder?


Did something perhaps change on the builder in the past couple of weeks?

We did a build recently for a new release and we are getting errors that aren’t really related to any of the code changes.

Also, we went back to the old version of the code…the code which is currently functioning just fine in our production release…and rebuilt with the old code and we’re getting the same errors.

Based on this, the errors we are seeing seem to be related to a build change…I feel like this is basically confirmed by having the old build fully functional but any new builds (using the same code) are throwing errors.

Hey @jhorner,

Can you elaborate on what you mean by errors? Specific error messages would go a long way in helping us get to the bottom of this.



Hi @adamjnav,


The issue we are experiencing is only in the actual APK (cannot be reproduced while debugging locally). Also, it only occurs on Android API 26 or greater (Android API < 26 and iOS has no issue).

The issue we are experiencing is only happening with builds after Sept 29, 2018. Please note, the same code giving us an issue today is live and functional in our current production build (which was built 9/29).

Expo: 27.1.1
Mobx: ^4.3.0

The issue is when we take an observable map and make an array from the map and filter the values.

let _map = new Map();
// **populate map with 150 entries

// **get an filtered array from the map
return Array.from(_map.values()).filter(entry => 
    entry.id === 133

This is a simplified version of our code but the basic premise of the issue is that when we go to filter an entry whose index is greater than 132, the app crashes because the entry is undefined.

Still spending some time to hunt down the root cause. My concerns related to expo is that I took the same exact code that is in our current (functional) production build and rebuilt it and I’m getting the same issue (as we see in our latest code base). So I can’t see how the issue is a code change as we have something out there working today…only when we do new builds does the issue show itself.

Upgrading to the latest SDK (30) seems to have resolved our issue.

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