Whenever I try to join my friend's Minecraft server it says "Internal server error". Or sometimes bj cannot be cast to fs.

How can I fix this problem?

  • Do you have the Permissions EX plugin installed? – BitNinja Apr 23 '14 at 0:54
  • Wow, I have absolutely no idea what you are talking about... – DatEpicCoderGuyWhoPrograms Apr 23 '14 at 12:39
  • Something is wrong with your friends server(i think) he probably didnt do something right now ask him if the server is bukkit(he'll understand if it is)and ask him if he has permissions EX installed and did he use a program to port forward or not check thi slink minecraftforum.net/topic/1486634-internal-server-error i think it might help – LFM Apr 24 '14 at 23:35
  • I have the same issue, but it's wierd; I can't get on with my old account (W01fy), which is a Legacy Minecraft Account, and I used to be able to. My friend Tyler, whose account is also Legacy (Tylerblaze48), got the same issue tonight (it's like 20 past 8 at night here at the moment). And yet I never get it with my new Mojang minecraft account (made using a Mojang account) – user83574 Jul 31 '14 at 10:19

This was an issue a server I hosted for many moons had. In the end, in my case it ended up being a router that simply didn't port forward properly despite all proper configuration. If your friend is hosting out of their home, and their router supports DMZing a specific ip, I would recommend briefly testing to see if that solves the problem. It's not a long term solution unless your friend has a dedicated box he's hosting it on and is confident in how the server is hardened, but it's a good test to reduce the probability that the router is the culprit.

If it's a hosted server... I've no tips for you. :)


WARNING SAVE SERVER BEFORE CONTINUING I fixed this problem, I just recently encountered this with my families two oldest minecraft accounts. What I did was look at server log, It said:

[10:43:56 INFO]: UUID of player ************ is aa5aa98e-8e15-4176-9c23-f602d29eb998
[10:43:56 WARN]: Failed to handle packet for /
i: Non [a-z0-9/._-] character in path of location: minecraft:EntityHorse
at pc.<init>(SourceFile:38) ~[minecraft_server.1.13.jar:?]
at pc.<init>(SourceFile:43) ~[minecraft_server.1.13.jar:?]
at wn.a(SourceFile:121) ~[minecraft_server.1.13.jar:?]
at wn.a(SourceFile:100) ~[minecraft_server.1.13.jar:?]
at wn.<init>(SourceFile:48) ~[minecraft_server.1.13.jar:?]
at vo.a(SourceFile:915) ~[minecraft_server.1.13.jar:?]
at te.<init>(SourceFile:159) ~[minecraft_server.1.13.jar:?]
at vo.g(SourceFile:442) ~[minecraft_server.1.13.jar:?]
at ud.b(SourceFile:113) ~[minecraft_server.1.13.jar:?]
at ud.Y_(SourceFile:65) ~[minecraft_server.1.13.jar:?]
at hw.a(SourceFile:238) ~[minecraft_server.1.13.jar:?]
at ua.c(SourceFile:171) [minecraft_server.1.13.jar:?]
at net.minecraft.server.MinecraftServer.w(SourceFile:749) [minecraft_server.1.13.jar:?]
at sn.w(SourceFile:357) [minecraft_server.1.13.jar:?]
at net.minecraft.server.MinecraftServer.v(SourceFile:656) [minecraft_server.1.13.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:559) [minecraft_server.1.13.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_171]
[10:43:56 INFO]: com.mojang.authlib.GameProfile@739935ca[id=aa5aa98e-8e15-4176-9c23-f602d29eb998,name=********,properties={textures=com.mojang.authlib.properties.Property@7055b05f]},legacy=false] (/ lost connection: Internal server error

what I did is take the player ID which in this case is aa5aa98e-8e15-4176-9c23-f602d29eb998 as seen in line:

[10:43:56 INFO]: UUID of player ************ is aa5aa98e-8e15-4176-9c23-f602d29eb998

the 10:43:56 is time you can ignore it. anyway go into your server folder, not the individual folders, but the main folder that holds it all and at the top right you should have windows search. search the folder for the ID: aa5aa98e-8e15-4176-9c23- f602d29eb998

WARNING SAVE SERVER BEFORE DELETING when it pops up with all files with that name, delete them all, WARNING SAVE SERVER BEFORE DELETING

load server and try logging in now

note: all ids are different this one wont work because it is one of mine, try logging into world than look at server log that will give info above. That should say what the name of player is that failed and its ID.

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