After upgrading to Java 8u271, Symantec Protection Engine (SPE) or the server it is installed on exhibit one or more of the following behaviors until the service is restarted or the machine is rebooted:
There were changes in Java 8u271 that have caused instability in the local Java UI component of Protection Engine.
SPE 7.9+ with the Java UI enabled
SPSS 6.0.8+ with SPE 7.9+ and Java UI enabled
This issue appears to be resolved in 8u291. Please upgrade to 8u291 or newer.