if Unity gets installed to a folder with spaces in its name, AssemblyUpdater fails silently which may lead to edit time as well as at runtime errors.

This issue manifest itself as errors of types / members not being found like called non-existent method System.Boolean UnityEngine.VR.VRSettings::get_enabled() when trying to do purchases through IAP (more details about this specific case can be found in this forum thread: https://forum.unity.com/threads/exception-error-called-non-existent-method-system-boolean-unityengine-vr-vrsettings-get_enabled.518868/#post-3541537)

The issue was introduced in Unity version 2019.1.0a12 (build #6653) released on December 14, 2018

The simplest workaround for now is to install Unity to a path without spaces.

To verify that AssemblyUpdater.exe has actually changed assemblies look Editor.log for lines like:

[AssemblyUpdater] Type reference 'UnityEngine.VR.VRSettings' replaced with 'UnityEngine.XR.XRSettings' as the declaring type of 'System.Boolean UnityEngine.VR.VRSettings::get_enabled()' in 'System.Void UnityEngine.Purchasing.GooglePlayAndroidJavaStore::Purchase(System.String,System.String) {IL_0026: call System.Boolean UnityEngine.VR.VRSettings::get_enabled()}'.