Updating to new player format fails

[16:48:39] [Server thread/INFO]: Starting minecraft server version 1.7.6
[16:48:39] [Server console handler/ERROR]: Exception handling console input
java.io.IOException: De ingang is ongeldig
	at java.io.FileInputStream.readBytes(Native Method) ~[?:1.7.0_51]
	at java.io.FileInputStream.read(Unknown Source) ~[?:1.7.0_51]
	at java.io.BufferedInputStream.read1(Unknown Source) ~[?:1.7.0_51]
	at java.io.BufferedInputStream.read(Unknown Source) ~[?:1.7.0_51]
	at sun.nio.cs.StreamDecoder.readBytes(Unknown Source) ~[?:1.7.0_51]
	at sun.nio.cs.StreamDecoder.implRead(Unknown Source) ~[?:1.7.0_51]
	at sun.nio.cs.StreamDecoder.read(Unknown Source) ~[?:1.7.0_51]
	at java.io.InputStreamReader.read(Unknown Source) ~[?:1.7.0_51]
	at java.io.BufferedReader.fill(Unknown Source) ~[?:1.7.0_51]
	at java.io.BufferedReader.readLine(Unknown Source) ~[?:1.7.0_51]
	at java.io.BufferedReader.readLine(Unknown Source) ~[?:1.7.0_51]
	at lu.run(SourceFile:79) [minecraft_server.1.7.6.exe:?]
[16:48:40] [Server thread/INFO]: Loading properties
[16:48:40] [Server thread/INFO]: Default game type: SURVIVAL
[16:48:40] [Server thread/INFO]: Generating keypair
[16:48:40] [Server thread/INFO]: Starting Minecraft server on *:25565
[16:48:43] [Server thread/WARN]: Could not lookup user uuid for player
com.mojang.authlib.exceptions.AuthenticationUnavailableException: Cannot contact authentication server
	at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:69) ~[minecraft_server.1.7.6.exe:?]
	at com.mojang.authlib.yggdrasil.YggdrasilGameProfileRepository.findProfilesByNames(YggdrasilGameProfileRepository.java:45) [minecraft_server.1.7.6.exe:?]
	at ny.a(SourceFile:58) [minecraft_server.1.7.6.exe:?]
	at ny.a(SourceFile:358) [minecraft_server.1.7.6.exe:?]
	at ls.aE(SourceFile:422) [minecraft_server.1.7.6.exe:?]
	at ls.e(SourceFile:151) [minecraft_server.1.7.6.exe:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:339) [minecraft_server.1.7.6.exe:?]
	at li.run(SourceFile:628) [minecraft_server.1.7.6.exe:?]
Caused by: java.io.IOException: Server returned HTTP response code: 503 for URL: https://api.mojang.com/profiles/page/1
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source) ~[?:1.7.0_51]
	at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source) ~[?:1.7.0_51]
	at com.mojang.authlib.HttpAuthenticationService.performPostRequest(HttpAuthenticationService.java:83) ~[minecraft_server.1.7.6.exe:?]
	at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:52) ~[minecraft_server.1.7.6.exe:?]
	... 7 more
[16:48:43] [Server thread/ERROR]: Conversion failed, please try again later
og: Could not request user player from backend systems
	at oe.onProfileLookupFailed(SourceFile:331) ~[minecraft_server.1.7.6.exe:?]
	at com.mojang.authlib.yggdrasil.YggdrasilGameProfileRepository.findProfilesByNames(YggdrasilGameProfileRepository.java:90) ~[minecraft_server.1.7.6.exe:?]
	at ny.a(SourceFile:58) ~[minecraft_server.1.7.6.exe:?]
	at ny.a(SourceFile:358) [minecraft_server.1.7.6.exe:?]
	at ls.aE(SourceFile:422) [minecraft_server.1.7.6.exe:?]
	at ls.e(SourceFile:151) [minecraft_server.1.7.6.exe:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:339) [minecraft_server.1.7.6.exe:?]
	at li.run(SourceFile:628) [minecraft_server.1.7.6.exe:?]
Caused by: com.mojang.authlib.exceptions.AuthenticationUnavailableException: Cannot contact authentication server
	at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:69) ~[minecraft_server.1.7.6.exe:?]
	at com.mojang.authlib.yggdrasil.YggdrasilGameProfileRepository.findProfilesByNames(YggdrasilGameProfileRepository.java:45) ~[minecraft_server.1.7.6.exe:?]
	... 6 more
Caused by: java.io.IOException: Server returned HTTP response code: 503 for URL: https://api.mojang.com/profiles/page/1
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source) ~[?:1.7.0_51]
	at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source) ~[?:1.7.0_51]
	at com.mojang.authlib.HttpAuthenticationService.performPostRequest(HttpAuthenticationService.java:83) ~[minecraft_server.1.7.6.exe:?]
	at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:52) ~[minecraft_server.1.7.6.exe:?]
	at com.mojang.authlib.yggdrasil.YggdrasilGameProfileRepository.findProfilesByNames(YggdrasilGameProfileRepository.java:45) ~[minecraft_server.1.7.6.exe:?]
	... 6 more
[16:48:43] [Server thread/WARN]: **** DETECTED OLD PLAYER FILES IN THE WORLD SAVE
[16:48:43] [Server thread/WARN]: **** THIS USUALLY HAPPENS WHEN THE AUTOMATIC CONVERSION FAILED IN SOME WAY
[16:48:43] [Server thread/WARN]: ** please restart the server and if the problem persists, remove the directory 'world\players'