Server keeps crashing -- Help!!!

19.02 15:47:07 [Server] ERROR ------------------------------

19.02 15:47:07 [Server] ERROR java.lang.ref.Reference$ReferenceHandler.run(Unknown Source)

19.02 15:47:07 [Server] ERROR java.lang.Object.wait(Object.java:503)

19.02 15:47:07 [Server] ERROR java.lang.Object.wait(Native Method)

19.02 15:47:07 [Server] ERROR Stack:

19.02 15:47:07 [Server] ERROR PID: 2 | Suspended: false | Native: false | State: WAITING

19.02 15:47:07 [Server] ERROR Current Thread: Reference Handler

19.02 15:47:07...

Server keeps crashing -- Help!!!