android/view/view$onUnhandledKeyEventListener (onMeasure error)

I had a problem in creating a new project in Android studio 3.1.3, whenever I created a project the design layout will throw an error message:

Failed to load AppCompat ActionBar with unknown error.

error screenshot:

warning screenshot:

style.xml (while error)-->

<resources>

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

And I solved with by adding:

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

As showed in a other post

But when I needed to add a toolbar I stuck with the error:

android/view/view$onUnhandledKeyEventListener

error screenshot:

The problem is the app doesn't have actionbar, even though the style.xml have the appropriate code and toolbar never shows up even by changing the Layout_width, Layout_height and by constrainting it to the constraint layout.

I found the answer, but I'm not sure this is the best answer. But this fix all the issue.

The error could be because of a bug in the API 28.0.0-alpha3 which may mess around with the backward compatibility (I'm not completely sure about it yet).

build.gradle(Module: app) (before fix)-->

build.gradle(Module: app)

compileSdkVersion 28

targetSdkVersion 28

implementation 'com.android.support:appcompat-v7:28.0.0-alpha3'

I fixed the error by reducing the API version to 27.1.1 and changing the compileSdkVersion, targetSdkVersion and implementation.

build.gradle(Module: app)(after fixing error) -->

build.gradle(Module: app)

To fix the error just change

compileSdkVersion 27

targetSdkVersion 27

implementation 'com.android.support:appcompat-v7:27.1.1'

And Re-build the Gradle. This will clear all the error and warning about the ActionBar and toolbar.

no error and working toolbar