After logging out of server I just stopped the server and this showed up.

[17:56:12] [Server thread/INFO]: MarekZeman91 left the game
stop
[18:13:05] [Server thread/INFO]: Stopping the server
[18:13:05] [Server thread/INFO]: Stopping server
[18:13:05] [Server thread/INFO]: Saving players
[18:13:05] [Server thread/INFO]: Saving worlds
[18:13:05] [Server thread/INFO]: Saving chunks for level 'world'/Overworld
[18:13:05] [Server thread/INFO]: Saving chunks for level 'world'/Nether
[18:13:05] [Server thread/INFO]: Saving chunks for level 'world'/The End
[18:13:05] [Server Shutdown Thread/INFO]: Stopping server
[18:13:05] [Server Shutdown Thread/INFO]: Saving players
2014-01-16 18:13:05,606 ERROR Attempted to append to non-started appender ServerGuiConsole
Exception in thread "Server Shutdown Thread" org.apache.logging.log4j.core.appender.AppenderLoggingException: Attempted to append to non-started appender ServerGuiConsole
at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:89)
at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:425)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:406)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:367)
at org.apache.logging.log4j.core.Logger.log(Logger.java:110)
at org.apache.logging.log4j.spi.AbstractLogger.info(AbstractLogger.java:1011)
at net.minecraft.server.MinecraftServer.n(SourceFile:312)
at ls.run(SourceFile:635)
logout

[Process completed]