Rendering Problems The following classes could not be instantiated:
- android.support.v7.app.WindowDecorActionBar (Open Class, Show Exception, Clear Cache)
 Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE.  If this is an unexpected error you can also try to build the project, then manually refresh the layout.
 
java.lang.NullPointerException
	at android.support.v7.app.WindowDecorActionBar.getDecorToolbar(WindowDecorActionBar.java:241)
	at android.support.v7.app.WindowDecorActionBar.init(WindowDecorActionBar.java:197)
	at android.support.v7.app.WindowDecorActionBar.(WindowDecorActionBar.java:189)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:465)
	at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:172)
	at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:105)
	at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadView(LayoutlibCallbackImpl.java:186)
	at com.android.layoutlib.bridge.bars.AppCompatActionBar.(AppCompatActionBar.java:89)
	at com.android.layoutlib.bridge.impl.Layout.createActionBar(Layout.java:238)
	at com.android.layoutlib.bridge.impl.Layout.(Layout.java:150)
	at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:301)
	at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:429)
	at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:389)
	at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:548)
	at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:533)
	at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:966)
	at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:533)
	at com.android.tools.idea.rendering.RenderTask.lambda$inflate$72(RenderTask.java:659)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

Modify the res/values/styles.xml directory:

style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">

for:

<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">