Sever not starting

[PROJECTInfinity234]

Hello Minehut comunity,

I am having an error while starting up m server, it starts up normal at first, but then it gives me this message in the log. I really don't understand whats going on but can anyone help. (btw the sever ips are rattok720p and ratcamp123

[22:30:07 WARN]: **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!

[22:30:07 WARN]: The server will make no attempt to authenticate usernames. Beware.

[22:30:07 WARN]: Whilst this makes it possible to use BungeeCord, unless access to your server is properly restricted, it also opens up the ability for hackers to connect with any username they choose.

[22:30:07 WARN]: Please see http://www.spigotmc.org/wiki/firewall-guide/ for further information.

[22:30:07 WARN]: To change this, set "online-mode" to "true" in the server.properties file.

[22:30:07 INFO]: Preparing level "world"

[22:30:08 INFO]: Preparing start region for dimension minecraft:overworld

[22:30:09 WARN]: java.lang.RuntimeException: Server attempted to load chunk saved with newer version of minecraft! 2730 > 2586

[22:30:09 WARN]: 	at net.minecraft.server.v1_16_R3.ChunkRegionLoader.loadChunk(ChunkRegionLoader.java:111)

[22:30:09 WARN]: 	at com.destroystokyo.paper.io.chunk.ChunkLoadTask.executeTask(ChunkLoadTask.java:114)

[22:30:09 WARN]: 	at com.destroystokyo.paper.io.chunk.ChunkLoadTask.run(ChunkLoadTask.java:39)

[22:30:09 WARN]: 	at com.destroystokyo.paper.io.QueueExecutorThread.pollTasks(QueueExecutorThread.java:105)

[22:30:09 WARN]: 	at com.destroystokyo.paper.io.QueueExecutorThread.run(QueueExecutorThread.java:38)

/home/minecraft/signal/start_cmd: line 1:  1053 Killed                  /opt/java/11/bin/java -Xmx${SERVER_RAM} -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -DIReallyKnowWhatIAmDoingISwear -Djline.terminal=jline.UnsupportedTerminal --illegal-access=permit -Dlog4j2.formatMsgNoLookups=true -jar server.jar