SfRadialMenu android compatibility: API level 21+ only ?!!!!
I/MonoDroid( 5075): UNHANDLED EXCEPTION:
I/MonoDroid( 5075): Java.Lang.NoClassDefFoundError: android/util/Size ---> Java.Lang.ClassNotFoundException: Didn't find class "android.util.Size" on path: DexPathList[[zip file "/data/app/com.webscopemobility.WSMClient-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.webscopemobility.WSMClient-1, /vendor/lib, /system/lib]]
I/MonoDroid( 5075): --- End of inner exception stack trace ---
MonoDroid( 5075): at Java.Interop.JniEnvironment+Types.FindClass (System.String classname) [0x00137] in <a043032cf94a485190047a14918b9f60>:0
I/MonoDroid( 5075): at Java.Interop.JniType..ctor (System.String classname) [0x00007] in <a043032cf94a485190047a14918b9f60>:0
I/MonoDroid( 5075): at Java.Interop.JniType.GetCachedJniType (Java.Interop.JniType& cachedType, System.String classname) [0x00024] in <a043032cf94a485190047a14918b9f60>:0
I/MonoDroid( 5075): at Java.Interop.JniPeerMembers.get_JniPeerType () [0x0000d] in <a043032cf94a485190047a14918b9f60>:0
I/MonoDroid( 5075): at Java.Interop.JniPeerMembers+JniInstanceMethods.get_JniPeerType () [0x0000e] in <a043032cf94a485190047a14918b9f60>:0
I/MonoDroid( 5075): at Java.Interop.JniPeerMembers+JniInstanceMethods.StartCreateInstance (System.String constructorSignature, System.Type declaringType, Java.Interop.JniArgumentValue* parameters) [0x00049] in <a043032cf94a485190047a14918b9f60>:0
I/MonoDroid( 5075): at Android.Util.Size..ctor (System.Int32 width, System.Int32 height) [0x00061] in <b0e1d100b79b4c5eb574c0acb2b1be12>:0
I/MonoDroid( 5075): at Syncfusion.SfRadialMenu.Android.CircleLayout.Initialize () [0x0010f] in <ab4aabd8171a46c9979e0b588ec383d1>:0
Android.Util.Size is API 21+
This means your component is API 21+ (android 5.1+)
So not compatible with Android 4.4 (api level 19)