java.lang.NoClassDefFoundError:

java.lang.NoClassDefFoundError: javax/faces/context/FacesContextFactory
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:270)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1701)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:270)
        at javax.faces.FactoryFinder.getImplGivenPreviousImpl(FactoryFinder.java:618)
        at javax.faces.FactoryFinder.getImplementationInstance(FactoryFinder.java:509)
        at javax.faces.FactoryFinder.access$400(FactoryFinder.java:139)
        at javax.faces.FactoryFinder$FactoryManager.getFactory(FactoryFinder.java:993)
        at javax.faces.FactoryFinder.getFactory(FactoryFinder.java:343)
        at com.sun.faces.config.processor.FactoryConfigProcessor.verifyFactoriesExist(FactoryConfigProcessor.java:303)
        at com.sun.faces.config.processor.FactoryConfigProcessor.process(FactoryConfigProcessor.java:219)
        at com.sun.faces.config.ConfigManager.initialize(ConfigManager.java:360)

        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>8.0</version>
        </dependency>

        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.2.20</version>
        </dependency>

        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.2.20</version>
        </dependency>