Hi Mario, We also found the same errors when we instrumented AppD Java Agent v21.1.0 and above with JRE 11 and Tomcat 8/9 combinations.  We have an active ticket with AppD support, and as per latest findings, even v21.11.3 (updated for log4j) is showing the same error messages in the application startup. One of the recent findings is that when we use -Djava.util.logging.manager=org.apache.logging.log4j.jul.LogManager, the errors showed up in all versions, where as if we use -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager, the error messages are suppressed. We use log4j.jul.LogManager for a specific purpose, overriding the default value set in Tomcat's setenv.sh file and ran into these exceptions/errors in the application startup. Not sure if this setting is supported in JRE 11 and how its conflicting with the default ClassLoaderLogManager class. It would be beneficial to review this issue in details as its impacting AppD agent use for JDK/JRE 11+. Regards, Senthil ... View more