When closing the server with the /stop command I sometimes get this error message. I feel like this issue could also be causing issues with players where sometimes with only two players the server will have lag and I will give the error "player XXX moved unexpectedly". This is the error:

C:\Daten\Minecraft - Server\minecraft_server.1.8.1 vanilla>java -Xmx5G -Xms5G -j
ar minecraft_server.1.8.1.jar -o false -d64
[14:05:02] [Server thread/INFO]: Starting minecraft server version 1.8.1
[14:05:02] [Server thread/INFO]: Loading properties
[14:05:02] [Server thread/INFO]: Default game type: SURVIVAL
[14:05:02] [Server thread/INFO]: Generating keypair
[14:05:02] [Server thread/INFO]: Starting Minecraft server on *:25565
[14:05:02] [Server thread/INFO]: Using default channel type
[14:05:02] [Server thread/WARN]: **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE
!
[14:05:02] [Server thread/WARN]: The server will make no attempt to authenticate
usernames. Beware.
[14:05:02] [Server thread/WARN]: While this makes the game possible to play with
out internet access, it also opens up the ability for hackers to connect with an
y username they choose.
[14:05:02] [Server thread/WARN]: To change this, set "online-mode" to "true" in
the server.properties file.
[14:05:02] [Server thread/INFO]: Preparing level "world"
[14:05:02] [Server thread/INFO]: Preparing start region for level 0
[14:05:03] [Server thread/INFO]: Preparing spawn area: 50%
[14:05:03] [Server thread/INFO]: Done (1,507s)! For help, type "help" or "?"
[14:05:21] [Server thread/INFO]: Aidas[/84.58.220.206:50229] logged in with enti
ty id 333 at (-292.69999998807907, 75.8500000178814, -880.3425035078519)
[14:05:21] [Server thread/INFO]: Aidas joined the game
[14:13:20] [Server thread/INFO]: Aidas lost connection: TextComponent{text='Disc
onnected', siblings=[], style=Style{hasParent=false, color=null, bold=null, ital
ic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, ins
ertion=null}}
[14:13:20] [Server thread/INFO]: Aidas left the game
stop
[14:13:25] [Server thread/INFO]: Stopping the server
[14:13:25] [Server thread/INFO]: Stopping server
[14:13:25] [Server thread/INFO]: Saving players
[14:13:25] [Server thread/INFO]: Saving worlds
[14:13:25] [Server thread/INFO]: Saving chunks for level 'world'/Overworld
[14:13:25] [Server thread/INFO]: Saving chunks for level 'world'/Nether
[14:13:25] [Server thread/INFO]: Saving chunks for level 'world'/The End
[14:13:25] [Server Shutdown Thread/INFO]: Stopping server
2015-02-14 14:13:25,926 ERROR Attempted to append to non-started appender File
2015-02-14 14:13:25,928 ERROR Unable to write to stream logs/latest.log for appe
nder File
2015-02-14 14:13:25,929 ERROR An exception occurred processing Appender File org
.apache.logging.log4j.core.appender.AppenderLoggingException: Error writing to R
andomAccessFile logs/latest.log
at org.apache.logging.log4j.core.appender.rolling.RollingRandomAccessFil
eManager.flush(RollingRandomAccessFileManager.java:109)
at org.apache.logging.log4j.core.appender.rolling.RollingRandomAccessFil
eManager.write(RollingRandomAccessFileManager.java:90)
at org.apache.logging.log4j.core.appender.OutputStreamManager.write(Outp
utStreamManager.java:129)
at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.a
ppend(AbstractOutputStreamAppender.java:113)
at org.apache.logging.log4j.core.appender.RollingRandomAccessFileAppende
r.append(RollingRandomAccessFileAppender.java:96)
at org.apache.logging.log4j.core.config.AppenderControl.callAppender(App
enderControl.java:99)
at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(Logge
rConfig.java:425)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.ja
va:406)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.ja
va: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.s(SourceFile:373)
at pf.run(SourceFile:716)
Caused by: java.io.IOException: Stream Closed
at java.io.RandomAccessFile.writeBytes(Native Method)
at java.io.RandomAccessFile.write(Unknown Source)
at org.apache.logging.log4j.core.appender.rolling.RollingRandomAccessFil
eManager.flush(RollingRandomAccessFileManager.java:106)
... 12 more

2015-02-14 14:13:25,937 ERROR Attempted to append to non-started appender Server
GuiConsole
Exception in thread "Server Shutdown Thread" org.apache.logging.log4j.core.appen
der.AppenderLoggingException: Attempted to append to non-started appender Server
GuiConsole
at org.apache.logging.log4j.core.config.AppenderControl.callAppender(App
enderControl.java:89)
at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(Logge
rConfig.java:425)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.ja
va:406)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.ja
va: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.s(SourceFile:373)
at pf.run(SourceFile:716)

C:\Daten\Minecraft - Server\minecraft_server.1.8.1 vanilla>pause
Drücken Sie eine beliebige Taste . . .