Reflections - Java 8 - invalid constant type

If you look at this table, you’ll see that “constant type: 18” refers to the CONSTANT_InvokeDynamic attribute whose tag value is 18.

So you are using a library which has a class parser which is not Java 8 compatible. Actually, this class parser even isn’t Java 7 compatible as this constant value is specified since Java 7. It just got away with that as ordinary Java code doesn’t use this feature in Java 7. But when interacting with code produced by different programming languages for the JVM, it could even fail with Java 7.

There’s an item in the bug tracker of Reflections describing your problem. At the bottom, you will find the notice:

With this fix: https://issues.jboss.org/browse/JASSIST-174 javassist got support for this constant. So with 3.18.2-GA this error doesn't occur.

I solved this problem that;

First upgrade javassist jar to -> 3.18.2-GA

  <dependency>
    <groupId>org.javassist</groupId>
    <artifactId>javassist</artifactId>
    <version>3.18.2-GA</version>
  </dependency>

Secondly add weblogic.xml

 <wls:package-name>javassist.*</wls:package-name>

I just fixed a similar issue here. In my case, there were two javassist jars on my class-path. I use maven and it was supposed to avoid that, but one of the dependencies used a different groupId (javassist for the old one and org.javassist for the new one, imported by org.reflections), so maven handled them as different artifacts.

I just changed the library depending the old one to depend on the new one and everything is fixed!