What are the common reasons for an Android app update installation to fail in user devices?

A portion of the users of the app in questions reported installation issues, when they click to install the update the process starts but it does not finish successfully.

Here is a summary of what changed between these versions:

• Version code was the same, but the build number was incremented
• One activity was changed to include the tag android:launchMode="singleTop"
• Replaced the deprecated fill_parent with match_parent
• Replaced android:gravity="right" for android:gravity="end"
• Replaced android:gravity="left" for android:gravity="start"
• Added android:layout_marginStart and android:layout_marginEnd where applicable

Is any of these changes known to cause installation issues in user devices? Any tip is greatly appreciated, because I do not understand how minor changes like these could lead to such issues. I've even halted the release roll-out in order to figure this out.

Update 1: I was able to reproduce one error in a test device, the error code is 944. What commonly causes this error?

I think I understood what happened, and it does not seem to be something caused by the app code.

I did some digging after finally seeing the error code and it turns out that error code 944 is caused by the fact that the Play Store servers are offline and can't answer the user's request.

Sources:

1. Android Authority
2. Android Pit