java.lang.NoClassDefFoundError is very common error yet takes some time to find the exact culprit and solution. if you are getting this then there must is a class which was present when you compile the code and got linked and now its not there when you trying to run, Its not easy to fix this problem because question which needs to be answer is why that class is not present now ? by the way you can follow some approach as suggested

This is because of incorrect Spring-Beans JRe. If you are using Maven, go to pom.xml, remove the spring-beans and add the version related to that of spring-core and spring-context. In my case, spring-beans was 1.2.x and others are 4.2.4. So I deleted spring-beans and added spring-beans 4.2.4 and resolved.