The 1.7.6 server version jar doesn't automatically parse the banlist from previous versions correctly, it can't parse date: 'Forever'.

[15:09:52] [Server thread/WARN]: Could not parse user banlist entry for xxxxr4336
java.text.ParseException: Unparseable date: "Forever"
at java.text.DateFormat.parse(Unknown Source) ~[?:1.7.0_51]
at oa.onProfileLookupSucceeded(SourceFile:94) [minecraft_server.1.7.6.jar:?]
at com.mojang.authlib.yggdrasil.YggdrasilGameProfileRepository.findProfilesByNames(YggdrasilGameProfileRepository.java:58) [minecraft_server.1.7.6.jar:?]
at ny.a(SourceFile:58) [minecraft_server.1.7.6.jar:?]
at ny.a(SourceFile:111) [minecraft_server.1.7.6.jar:?]
at ls.aE(SourceFile:417) [minecraft_server.1.7.6.jar:?]
at ls.e(SourceFile:151) [minecraft_server.1.7.6.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:339) [minecraft_server.1.7.6.jar:?]
at li.run(SourceFile:628) [minecraft_server.1.7.6.jar:?]