Adding Firebase Ads to Xamarin.Forms causes: Name cannot begin with the '$' character, hexadecimal value 0x24

Question

Windows ONLY This bug does NOT happen on a mac using the same solution.

Adding Firebase Ads to Xamarin.Forms causes: Name cannot begin with the '$' character, hexadecimal value 0x24 Visual studio shows this as a warning but it is actually stopping by the build.

1>DccClassCancelations.Android -> D:\dev\DccClassCancelationsLite\DccClassCancelations\DccClassCancelations\DccClassCancelations.Android\bin\Debug\DccClassCancelations.Android.dll 
1>No way to resolve conflict between "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" and "mscorlib, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e". Choosing "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" arbitrarily. 
1>Name cannot begin with the '$' character, hexadecimal value 0x24. 
1>C:\Program Files (x86)\Android\android-sdk\build-tools\25.0.3\zipalign.exe 4 "D:\dev\DccClassCancelationsLite\DccClassCancelations\DccClassCancelations\DccClassCancelations.Android\obj\Debug\android\bin\com.JacobErnst.DccClassCancelations.apk" "bin\Debug\\com.JacobErnst.DccClassCancelations-Signed.apk"  
1>C:\Program Files (x86)\Android\android-sdk\build-tools\25.0.3\apksigner.BAT sign --ks "C:\Users\jacob\AppData\Local\Xamarin\Mono for Android\debug.keystore" --ks-pass pass:android --ks-key-alias androiddebugkey --key-pass pass:android --min-sdk-version 15 --max-sdk-version 27  bin\Debug\com.JacobErnst.DccClassCancelations-Signed.apk  
1>"apksigner.BAT" exited with code 2. 
1>Done building project "DccClassCancelations.Android.csproj" -- FAILED. 
1>Build FAILED. 
1> 
1>Deploy failed on NExus6 ========== Deploy: 0 succeeded, 1 failed, 0 skipped ==========

No files in the visual studio solution have names starting with '$'

Steps to reproduce

1. Make a new Xamarin.Forms project
2. Install the Xamarin.Firebase.Ads package from NuGet
   • Use this link if you do not know how to use the Plugin
   • https://xamarinhelp.com/admob-xamarin-forms-display-google-ads-mobile-app/
3. Build the Android project

Answer 1

1>Name cannot begin with the '$' character, hexadecimal value 0x24. should not break your code. (Admittedly I've been ignoring this error for weeks now and I have no issue compiling).

From your output I would assume the issue is because 1>"apksigner.BAT" exited with code 2. From experience, I have had a similar issue as the result of a application size. Android has a limit of 65k methods that can easily be met when including Google Services. The solution is to enable multidex.

All in all, Name cannot begin with the '$' character should not cause a fatal error yet if my previous suggestion does not work, I suggest you look into renaming mscorlib properly (yet similarly unlikely to be the root of your problem) and then your signing process (without proper details I can't suggest a solution here, but errors while signing your apk will at the very least crash your app if not terminate the build) because