Case

I run a project with JSF 2 / PrimeFaces 5 (BTW: it rocks!) / Spring 4 / Jetty 9 / Java 8:

MultiException java.lang.RuntimeException: Error scanning file SummerBean.class, java.lang.RuntimeException: Error scanning entry .../SummerService.class from jar file:/.../spring-tier-1.0-SNAPSHOT.jar, java.lang.RuntimeException: Error scanning entry .../SummerServiceImpl.class from jar file:/.../spring-tier-1.0-SNAPSHOT.jar
        at org.eclipse.jetty.annotations.AnnotationConfiguration.scanForAnnotations(AnnotationConfiguration.java:530)

Explanation

The error occurs because of a conflict on the JARs of ASM.

Fix

You have to override Jetty’s dependencies to ASM.
In Maven’s POM, amend Jetty plugin to force ASM versions:

<plugin>
   <groupId>org.eclipse.jetty</groupId>
   <artifactId>jetty-maven-plugin</artifactId>
   <version>${jetty.version}</version>
   <dependencies>
      <dependency>
         <groupId>org.ow2.asm</groupId>
         <artifactId>asm</artifactId>
         <version>5.0.2</version>
         </dependency>
         <dependency>
         <groupId>org.ow2.asm</groupId>
         <artifactId>asm-commons</artifactId>
         <version>5.0.2</version>
         </dependency>
      </dependencies>
<!-- ... -->
</plugin>

Then it should work 😉