my server closed and I do not know why

my server closed and I do not know why, I enter and soon after it closed, without abyss and also started again but not let me in, I do not know why someone helps me, I do not have serverlog.
when I "start" it puts this ....

I have a not very big world with many npcs

here it is
[14:17:03] [Server thread/INFO]: Starting minecraft server version 1.11.2
[14:17:10] [Server thread/INFO]: Loading properties
[14:17:10] [Server thread/INFO]: Default game type: SURVIVAL
[14:17:10] [Server thread/INFO]: Generating keypair
[14:17:11] [Server thread/INFO]: Starting Minecraft server on *:47212
[14:17:11] [Server thread/INFO]: Using epoll channel type
[14:17:11] [Server thread/WARN]: **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!
[14:17:11] [Server thread/WARN]: The server will make no attempt to authenticate usernames. Beware.
[14:17:11] [Server thread/WARN]: While this makes the game possible to play without internet access, it also opens up the ability for hackers to connect with any username they choose.
[14:17:11] [Server thread/WARN]: To change this, set "online-mode" to "true" in the server.properties file.
[14:17:12] [Server thread/INFO]: Preparing level "world"
[14:17:14] [Server thread/INFO]: Preparing start region for level 0
[14:17:17] [Server thread/INFO]: Preparing spawn area: 0%
[14:17:19] [Server thread/INFO]: Preparing spawn area: 4%
[14:17:20] [Server thread/INFO]: Preparing spawn area: 30%
[14:17:21] [Server thread/INFO]: Preparing spawn area: 66%
[14:17:22] [Server thread/INFO]: Done (10.117s)! For help, type "help" or "?"
[14:17:22] [Server thread/INFO]: Starting GS4 status listener
[14:17:22] [Query Listener #1/INFO]: Query running on 0.0.0.0:57212

thank you all, but the server already works, I do not know why but right now it's fine, after publishing it it was well, but equally thanks