ADDITIONAL SYSTEM INFORMATION :
Server VM is OpenJDK Java 8 on RHEL 7.4 and the JConsole was Java 15 on Mac OS.
A DESCRIPTION OF THE PROBLEM :
When you connect JConsole that ships with Java 15 to a VM running an older version of Java like Java 8 for example it attempts to access an attribute called TotalMemorySize. This attribute does not exist in the older VMs and results in an Exception which is uncaught. That results in the connection being disconnected.
STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Try connecting JConsole (Java 15) to a Java VM (Version 8). The connection will get closed within 10 seconds. It does not appear to be a function of the OS either end is running on.
EXPECTED VERSUS ACTUAL BEHAVIOR :
Possibly some properties on the screen being absent or NA due to the inability to compute whatever that value is used to compute. Maybe an error dialog or something saying this version of JConsole is not compatible with the older version of Java.
Unchecked exception kills the connection.
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No need. This happens on the raw VM
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CUSTOMER SUBMITTED WORKAROUND :
Downgrade the Java client or Update the Server VM.
FREQUENCY : always