java.lang.ClassNotFoundException: java.lang.constant.Constable after upgrading libraries

Question

I have an application running in Tomcat 9.0.45 with JDK 11 (OpenJDK 11.0.11).

After upgrading some libraries (Spring 4.3.30 to 5.3.9) using maven, the application throws the following Exception:

java.lang.NoClassDefFoundError: java/lang/constant/Constable
    at my.app.SomeClass.process(SomeClass.java:123) ~[classes/:?]
    at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) [spring-context-5.3.9.jar:5.3.9]
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) [?:?]
    at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) [?:?]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
    at java.base/java.lang.Thread.run(Thread.java:829) [?:?]
Caused by: java.lang.ClassNotFoundException: java.lang.constant.Constable
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1364) ~[catalina.jar:9.0.45]
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1187) ~[catalina.jar:9.0.45]
    ... 11 more

Obviously, it tries to run JRE 12 code in a JRE 11 environment.

As the Exception does not occur prior to updating the libraries, I guess some dependency got into the project that uses the JRE 12 code.

How can I find out which library/dependency causes the problem?

WebappClassLoaderBase debug log does not give any new information:

org.apache.catalina.loader.WebappClassLoaderBase.loadClass loadClass(java.lang.constant.Constable, false)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass   Searching local repositories
org.apache.catalina.loader.WebappClassLoaderBase.findClass     findClass(java.lang.constant.Constable)
org.apache.catalina.loader.WebappClassLoaderBase.findClass     --> Returning ClassNotFoundException

Strangely, the Exception does not occur on my dev machine, so I also can't debug.

Any ideas are very much appreciated.

Edit: compiling with maven 3.8.1 using aspectj-maven-plugin 1.12.6.

Answer 1

@Stephen C pointed to the right direction - something has compiled something that way.

Turns out the machine that compiles the code, did not have Java 11 installed, but Java 16. (Still, that compiled perfectly runnable Java 11 code for Spring 4.3.30.)

I have removed Java 16 from the machine and installed Java 11 only. The code now runs without throwing the ClassNotFoundException.

As of why that happened, I still have no idea.