Bug 21485 - Android: Using a theme on an AndroidActivity causes NRE
Summary: Android: Using a theme on an AndroidActivity causes NRE
Status: RESOLVED DUPLICATE of bug 20459
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.2.2
Hardware: PC Windows
: Normal normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2014-07-21 13:09 UTC by rwakelan
Modified: 2015-02-02 01:45 UTC (History)
5 users (show)

Is this bug a regression?: ---
Last known good build:

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Description rwakelan 2014-07-21 13:09:13 UTC
If you create an Android Activity and add a Theme, it will cause a NRE to be thrown.  This theme doesn't have to do anything at all, a blank Theme style will cause this error to happen.

System.NullReferenceException: Object reference not set to an instance of an object
  at Xamarin.Forms.Platform.Android.Platform.UpdateActionBar () [0x00000] in <filename unknown>:0 
  at Xamarin.Forms.Platform.Android.Platform.SetPage (Xamarin.Forms.Page newRoot) [0x00000] in <filename unknown>:0 
  at Xamarin.Forms.Platform.Android.AndroidActivity.SetPage (Xamarin.Forms.Page page) [0x00000] in <filename unknown>:0 
  at [Activity].OnCreate (Android.OS.Bundle bundle) [0x0001f] in [Activity File]:[Line Number]

To anyone else encoutering this problem, my workaround was to create a non-AndroidActivity Activity that uses the Theme and then loads the first AndroidActivity Activity with "StartActivity" in the OnCreate handler.  This gets around the bug.

I've attached a sample reproduction of this bug.  Launch the app as is and it will show an error message for the NRE.  Comment out "Theme = "@style/Theme.Splash"," in the Activity header and the error will go away.  Theme.Splash is an empty theme, it does nothing.  This happens regardless of what the Theme does.
Comment 1 Eric Maupin 2014-07-22 16:27:44 UTC
Currently we only support themes that contain action bars. We're working on addressing this, but in the mean time you will have to limit which theme you select.
Comment 2 Jason Smith [MSFT] 2015-02-02 01:45:28 UTC

*** This bug has been marked as a duplicate of bug 20459 ***