Pete Nawara

Same issue running a multiplayer server.

Mac 10.8.3
snapshot 13w16a

server port changed to 25567 (not sure why, if it all, that would matter)

Here's my rundown... hope it helps!

Client> 2013-04-19 08:27:21 [CLIENT] [INFO] [CHAT] §7§o[Server: Opped gorganzoliator]
Client> 2013-04-19 08:27:30 [CLIENT] [INFO] [CHAT] Your game mode has been updated
Client> Creating hgr
Client> Creating hcrbdo
Client> Creating hgrwmo
Client> Creating hch
Client> Creating hbr
Client> Creating hblwdo
Client> Creating hcr
Client> java.lang.NullPointerException
Client> at ek.n(SourceFile:174)
Client> at ck.a(SourceFile:237)
Client> at ck.a(SourceFile:225)
Client> at ck.h(SourceFile:175)
Client> at ck.d(SourceFile:16)
Client> at cm.run(SourceFile:115)
Client> java.io.FileNotFoundException: http://assets.minecraft.net/1_6_has_been_released.flag
Client> at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1434)
Client> at kq.a(SourceFile:237)
Client> at bhq.run(SourceFile:114)
Client> at java.lang.Thread.run(Thread.java:680)