crash of server

Put the summary of the bug you're having here

*What I expected to happen was
enter my server:*
come in and play

What actually happened was...:

who said it was offline while someone was inside and eventually crashed

Steps to Reproduce:
1.
no I entered the server
2.
He said it was offline, but it was online
3.
server crash

---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 19/12/16 14.48
Description: Ticking screen

java.lang.NullPointerException: Ticking screen
	at io.netty.bootstrap.Bootstrap.checkAddress(Bootstrap.java:273)
	at io.netty.bootstrap.Bootstrap.doConnect(Bootstrap.java:150)
	at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:132)
	at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:113)
	at bnt.b(SourceFile:241)
	at bnt.a(SourceFile:45)
	at bnt$1.a(SourceFile:144)
	at er.l(SourceFile:382)
	at bnt.a(SourceFile:254)
	at bjd.e(SourceFile:115)
	at beq.t(SourceFile:1598)
	at beq.av(SourceFile:967)
	at beq.a(SourceFile:395)
	at net.minecraft.client.main.Main.main(SourceFile:124)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Client thread
Stacktrace:
	at io.netty.bootstrap.Bootstrap.checkAddress(Bootstrap.java:273)
	at io.netty.bootstrap.Bootstrap.doConnect(Bootstrap.java:150)
	at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:132)
	at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:113)
	at bnt.b(SourceFile:241)
	at bnt.a(SourceFile:45)
	at bnt$1.a(SourceFile:144)
	at er.l(SourceFile:382)
	at bnt.a(SourceFile:254)
	at bjd.e(SourceFile:115)

-- Affected screen --
Details:
	Screen name: bjd
Stacktrace:
	at beq.t(SourceFile:1598)
	at beq.av(SourceFile:967)
	at beq.a(SourceFile:395)
	at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
	Minecraft Version: 1.11
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 165221032 bytes (157 MB) / 369307648 bytes (352 MB) up to 1060372480 bytes (1011 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.11
	LWJGL: 2.9.4
	OpenGL: Intel(R) HD Graphics 520 GL version 4.4.0 - Build 20.19.15.4360, Intel
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

	Using VBOs: Yes
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: Faithful 1.11-rv2.zip
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	CPU: 4x Intel(R) Core(TM) i3-6100U CPU @ 2.30GHz