Failed to load AppCompat ActionBar with unknown error in android studio

Question

Below is my xml file. In preview there is two error'Failed to load AppCompat ActionBar with unknown error' & 'Failed to instaniate more than one class'. How ever am able to run the app.But the app crashes and in Logcat no errors are shown.

This is my preview screen shot

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">


    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="506dp" />

    <LinearLayout
        android:id="@+id/layout_main"
        android:orientation="vertical"
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:weightSum="1"
        tools:context=".Activity.MainActivity">


    <LinearLayout
        android:id="@+id/main_layout"
        android:orientation="vertical"
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="0.7"
        tools:context=".Activity.MainActivity">

        <!-- our tablayout to display tabs  -->
        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="50dp"
            app:tabMode="scrollable"
            app:tabSelectedTextColor="@color/colorBlack"
            app:tabTextColor="@color/colorWhite"
            android:background="@color/colorOran"
            android:minHeight="?attr/actionBarSize"
            />

        <!-- View pager to swipe views -->
        <android.support.v4.view.ViewPager
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

    </LinearLayout>

        <LinearLayout
            android:id="@+id/ll"
            android:layout_width="match_parent"
            android:layout_height="64dp"
            android:layout_alignParentBottom="true"
            android:background="#ffffff"
            android:orientation="horizontal"
            android:layout_weight="0.3"
            android:weightSum="4"
            tools:layout_editor_absoluteX="8dp"
            android:layout_marginBottom="8dp"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true">

            <ImageView
                android:id="@+id/btn_home"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:src="@drawable/ta_home_icon"
                android:background="@color/colorOran"
                android:layout_marginRight="1dp"
                android:scaleType="fitCenter"/>

            <ImageView
                android:id="@+id/btn_new"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:src="@drawable/ta_todaydeals_icon"
                android:background="@color/colorOran"
                android:layout_marginRight="1dp"
                android:scaleType="fitCenter"/>

            <ImageView
                android:id="@+id/btn_fav"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:src="@drawable/ta_fav_icon"
                android:background="@color/colorOran"
                android:layout_marginRight="1dp"
                android:scaleType="fitCenter"/>

            <ImageView
                android:id="@+id/btn_auth"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:src="@drawable/ta_franchie_icon"
                android:background="@color/colorOran"
                android:scaleType="fitCenter"
                android:layout_marginRight="1dp"
                />

        </LinearLayout>

    </LinearLayout>


    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />


</android.support.v4.widget.DrawerLayout>

Below is appbar_main

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.jeyashri.kitchen.jeyashriskitchen.Activity.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">


        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@color/colorOran"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <ImageView
                android:id="@+id/app_logo"
                android:layout_width="80dp"
                android:layout_height="match_parent"
                android:src="@drawable/img"/>

            <ImageView
                android:id="@+id/btn_social"
                android:layout_width="75dp"
                android:layout_height="35dp"
                android:layout_marginRight="1dp"
                android:src="@drawable/share_icon" />

    </android.support.v7.widget.Toolbar>

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />


</android.support.design.widget.CoordinatorLayout>

Answer 1

The solution to this problem depends on the version of the Android support library you're using:

Support library 26.0.0-beta2

This android support library version has a bug causing the mentioned problem

In your Gradle build file use:

compile 'com.android.support:appcompat-v7:26.0.0'

with:

buildToolsVersion '26.0.0' 

and

classpath 'com.android.tools.build:gradle:3.0.0-alpha8'

everything should work fine now.

---

Library version 28 (beta)

These new versions seem to suffer from similar difficulties again.

In your res/values/styles.xml modify the AppTheme style from

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

to

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

(note the added Base.)

Or alternatively downgrade the library until the problem is fixed:

implementation 'com.android.support:appcompat-v7:28.0.0-alpha1'