I have found the problem with classpath setting in JMX plugin. Try to replace jmx.jar on your system with this version: https://cloud.radensolutions.com/s/WDCCtmPKHXGZwyo.
If you installed agent on Linux from packages it will be inside /usr/lib/netxms/java.
Best regards,
Victor
If you installed agent on Linux from packages it will be inside /usr/lib/netxms/java.
Best regards,
Victor