JBoss EAP (WildFly) deletes the old "tmp/vfs/" directory by design. The same behavior occurs when the embed-server starts.

If embed-server is executed beside running server, it deletes the same "tmp/vfs" directory that the running server is currently using. This can result in an application error caused by NoClassDefFoundError due to missing class files that should exist in the "tmp/vfs" directory.

Also, note that JDR (JBOSS_HOME/bin/jdr.sh) can internally start the embed-server to gather information if it cannot connect to the specified host/port (localhsot:9990 by default). Therefore, if jdr.sh is invoked incorrectly by specifying the wrong IP address/port, it can cause deleting the same "tmp/vfs" directory that the running server is currently using. This can result in an application error caused by NoClassDefFoundError due to missing class files that should exist in the "tmp/vfs" directory.