classformatexception

Trying to Run Vaadin 8.1 app under Java 9 prerelease in IntelliJ 2017.2.2 I was able to build a vaadinjavanine.war using a fresh project and host the same using Jetty Server. I ended up trying to deploy the generated war to a tomcat server. But, during the startup of the tomcat server, I am getting the following exception: 21-Aug-2017 22:53:38.830 SEVERE [localhost-startStop-1] org.apache.catalina.startup.ContextConfig.processAnnotationsFile Unable to process file [/Library/Tomcat/apache-tomcat-8.0.22/webapps/vaadinjavanine/WEB-INF/classes/module-info.class] for annotations org.apache.tomcat

This question already has an answer here: org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 15 8 answers I tried upgrading to Java 8. When starting our tomcat7 server, with a Java 7-compiled .war file, I get the mysteriously error below. Should I expect this to work? This post says tomcat 7 should work with 1.6 and up. I can't tell if Tomcat is to blame, or the .war. Switching out different Java versions I get: JDK 7.45 installed - works (same version used to compile .war) JDK 7.55 installed - fails as below JDK 8.05 installed - fails as below Is