When entering a particular area, the server crashes with the following in the console:

[20:55:53 WARN]: Fetching addPacket for removed entity
[20:55:54 ERROR]: Encountered an unexpected exception
u: Exception ticking world
at net.minecraft.server.MinecraftServer.w(SourceFile:574) ~[minecraft_server.14w25b.jar:?]
at nt.w(SourceFile:284) ~[minecraft_server.14w25b.jar:?]
at net.minecraft.server.MinecraftServer.v(SourceFile:506) ~[minecraft_server.14w25b.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:422) [minecraft_server.14w25b.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.7.0_55]
Caused by: java.lang.IllegalArgumentException: Cannot set property ayl

{name=facing, clazz=class dt, values=[north, south, west, east]}

to down on block minecraft:wall_sign, it is not an allowed value
at aya.a(SourceFile:131) ~[minecraft_server.14w25b.jar:?]
at awb.a(SourceFile:57) ~[minecraft_server.14w25b.jar:?]
at ou.h(SourceFile:342) ~[minecraft_server.14w25b.jar:?]
at ou.c(SourceFile:179) ~[minecraft_server.14w25b.jar:?]
at net.minecraft.server.MinecraftServer.w(SourceFile:570) ~[minecraft_server.14w25b.jar:?]
... 4 more
[20:55:54 ERROR]: This crash report has been saved to: S:\Games\MineCraft\ORE.snapshot\.\crash-reports\crash-2014-06-24_20.55.54-server.txt

Problem is not resolved with Repair regions in MCedit. The crash report file has been attached.