Google has released a new version of Android SDK Tools (rev. 24.3.4). This version breaks the Xamarin.Android designer.
The fix for the designer Bug 33174 has now been released to the Stable channel:
If you still see Bug 33174 after updating, or if you find any additional bugs caused by Android SDK Tools (rev. 24.3.4), please file a bug report and add a comment back on this thread with the bug number. Thanks!
There are currently two known issues with the released builds. This post will be updated to reflect progress on these bugs, as updates are available
Private bug 33236 - On starting Xamarin Android Player with Xamarin Studio, IP address of Xamarin Android Player emulator displays in device configuration dropdown.
Private bug 33237 - Unable to start Xamarin Android Player emulator as it is displaying as an unsupported section in device list in VS.
ERROR: java.lang.NoSuchMethodError: com.android.ide.common.rendering.api.HardwareConfig.<init> (IILcom/android/resources/Density;FFLcom/android/resources/ScreenSize;Lcom/android/resources/ScreenOrientation;Z)V
If you do not want to upgrade yet, the below workaround is still valid. However, if you at any point want to upgrade to Android SDK Tools 24.3.4, then you will need to upgrade to the versions listed above.
Please post a screenshot of your SDK tools window. This is available via the following means:
Xamarin Studio : Tools >Open Android SDK Manager
Visual Studio : Tools > Android > Android SDK Manager
A compliant Android SDK Manager will look similar to the following screenshot, where an update is available to 24.3.4, but not installed: