migrate tomcat 6 to 7; JSF; java.lang.NoClassDefFoundError: com/sun/enterprise/InjectionException

I need to migrate a tomcat 6 project (Java 6) to a Tomcat 7 Server (Java 7). Right now i receive the following error(s) from the server:

SCHWERWIEGEND: Critical error during deployment: 
java.lang.NoClassDefFoundError: com/sun/enterprise/InjectionException
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:274)
    at com.sun.faces.util.Util.loadClass(Util.java:364)
    at com.sun.faces.spi.InjectionProviderFactory.getProviderFromEntry(InjectionProviderFactory.java:317)
    at com.sun.faces.spi.InjectionProviderFactory.findProviderClass(InjectionProviderFactory.java:285)
    at com.sun.faces.spi.InjectionProviderFactory.createInstance(InjectionProviderFactory.java:116)
    at com.sun.faces.config.ConfigManager.initialize(ConfigManager.java:365)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:227)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4992)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5492)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: com.sun.enterprise.InjectionException
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    ... 17 more

Jul 08, 2015 2:59:58 PM org.apache.catalina.core.StandardContext listenerStart
SCHWERWIEGEND: Exception sending context initialized event to listener instance of class com.sun.faces.config.ConfigureListener
java.lang.RuntimeException: java.lang.NoClassDefFoundError: com/sun/enterprise/InjectionException
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:292)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4992)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5492)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1575)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1565)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NoClassDefFoundError: com/sun/enterprise/InjectionException
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:274)
    at com.sun.faces.util.Util.loadClass(Util.java:364)
    at com.sun.faces.spi.InjectionProviderFactory.getProviderFromEntry(InjectionProviderFactory.java:317)
    at com.sun.faces.spi.InjectionProviderFactory.findProviderClass(InjectionProviderFactory.java:285)
    at com.sun.faces.spi.InjectionProviderFactory.createInstance(InjectionProviderFactory.java:116)
    at com.sun.faces.config.ConfigManager.initialize(ConfigManager.java:365)
    at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:227)
    ... 9 more
Caused by: java.lang.ClassNotFoundException: com.sun.enterprise.InjectionException
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    ... 17 more

Anyone any idea how to fix this, or even where to start?

Thanks in advance =)