Xamarin.Forms - MONO_GC_PARAMS=bridge-implementati

I'm seeing this cryptic exception that's been documented on bugzilla.xamarin.com periodically. Most of the posts suggest you can suppress the error by changing the bridge implementation to the Old version instead of Tarjan by setting an environment variable:

MONO_GC_PARAMS=bridge-implementation=old

I set the variable, but I don't see anything in my logcat or build output to indicate it's using one bridge or the other, and I'm still getting the exception. Is there a way to tell which implementation is being used?

Here's the stack trace - any suggestions are greatly appreciated.

 Process: com.icon.iconsurvey, PID: 11543
 android.runtime.JavaProxyThrowable: System.ArgumentException: Handle must be valid.
 Parameter name: instance
   at Java.Interop.JniEnvironment+InstanceMethods.CallNonvirtualVoidMethod (Java.Interop.JniObjectReference instance, Java.Interop.JniObjectReference type, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue* args) [0x00009] in <7cfbebb561c54efc9010b018c0846c7e>:0 
   at Android.Runtime.JNIEnv.CallNonvirtualVoidMethod (System.IntPtr jobject, System.IntPtr jclass, System.IntPtr jmethod, Android.Runtime.JValue* parms) [0x00015] in <e975227ac8644a30bb0866117325de0d>:0 
   at Android.Support.V4.Widget.DrawerLayout.RemoveDrawerListener (Android.Support.V4.Widget.DrawerLayout+IDrawerListener listener) [0x00088] in <fc4222de5c684a9abf7cc4821baac4cd>:0 
   at Xamarin.Forms.Platform.Android.AppCompat.NavigationPageRenderer.Dispose (System.Boolean disposing) [0x000e4] in <b5b1173f4d49442b898c45e26ae39e48>:0 
   at Java.Lang.Object.Dispose () [0x00000] in <e975227ac8644a30bb0866117325de0d>:0 
   at Xamarin.Forms.Platform.Android.AppCompat.Platform+<>c__DisplayClass35_0.<SetPage>b__0 () [0x00015] in <b5b1173f4d49442b898c45e26ae39e48>:0 
   at Java.Lang.Thread+RunnableImplementor.Run () [0x00008] in <e975227ac8644a30bb0866117325de0d>:0 
   at Java.Lang.IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this) [0x00008] in <e975227ac8644a30bb0866117325de0d>:0 
     at (wrapper dynamic-method) System.Object:1d7dae73-d3c1-4d29-aa82-708ecaa93ad1 (intptr,intptr)
     at mono.java.lang.RunnableImplementor.n_run(Native Method)
     at mono.java.lang.RunnableImplementor.run(RunnableImplementor.java:30)
     at android.os.Handler.handleCallback(Handler.java:739)
     at android.os.Handler.dispatchMessage(Handler.java:95)
     at android.os.Looper.loop(Looper.java:145)
     at android.app.ActivityThread.main(ActivityThread.java:6939)
     at java.lang.reflect.Method.invoke(Native Method)
     at java.lang.reflect.Method.invoke(Method.java:372)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)

The current suggestion is using new rather than old when changing the default GC Bridge away from tarjan. You may have been told to use the "old" default which was technically new before changing to tarjan in Mono 4.6:

http://www.mono-project.com/docs/about-mono/releases/4.6.0/#new-default-gc-bridge-processor-on-android

You can see if this is being picked up by checking the Diagnostic Build Output of your project.

https://developer.xamarin.com/guides/android/troubleshooting/troubleshooting/#Diagnostic_MSBuild_Output

You would then look to ensure the configuration file is picked up with the respective arguments.