Keystore file doesn't exist
Solution 1:
Linux & Mac command
keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android -keypass android
Will give you SHA1, SHA256, MD5 for default debug key. And it can be used for developing and debugging with google play services.
For publication certificate just follow https://developer.android.com/studio/publish/app-signing.html
Solution 2:
You said you are running the command from...
/Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/Contents/Home/bin
Is your keystore file in that directory as well? If not then you need to specify the path to the keystore file, e.g.
keytool -list -v -keystore ~/somefolder/mystore.keystore
The keystore used should be the one used to sign the app. For Xamarin debug builds this will be the debug keystore located at /Users/[USERNAME]/.local/share/Xamarin/Mono\ for\ Android/debug.keystore
. The command on OSX for this would be...
keytool -list -v -keystore /Users/[USERNAME]/.local/share/Xamarin/Mono\ for\ Android/debug.keystore -alias androiddebugkey -storepass android -keypass android
Or on Windows 7
keytool -list -v -keystore C:\Users\[USERNAME]\AppData\Local\Xamarin\Mono for Android\debug.keystore -alias androiddebugkey -storepass android -keypass android
Solution 3:
I faced the same issue, but resolved via following command:
keytool -exportcert -keystore C:\Users\<USERNAME>\.android\debug.keystore -list -v
OS: Windows 7