(I'm sorry for bad English, I'm not native speaker)


My Bukkit server in offline mod.

I tried to add an username in the game, for example, 'Bear' and used command '/reload'.

But in whitelist.json I saw 'bear' (with no capital). For sure Bear can't connect to server.

Then I turned off my server. In whitelist.json I changed 'bear' to 'Bear'. After this I run my server and in whitelist.json I saw 'bear'. Again.

Then I turned off my server. I deleted usernamecache.json. I run my server again. I added a new username in the game, for example, 'fox' and then '/reload'.

And what I saw in whitelist.json? 'FoX' and 'bear'!

Well, I turn off my server, I opened whitelist.json again and changed 'bear' to 'Bear' and 'FoX' to 'fox'. I turned on my server. After this usernames didn't changed: I saw 'Bear' and 'fox'. But this players still can't connect to my server.

To be honest, I don't remember very well sequencing, but I really tried to write it as accurate as it possible.

  • names are not case sensitive. are you sure the whitelist is the reason they cannot join? – Ender May 8 '15 at 3:12

First, you should not run your server in offline mode.

However, if you have to, you need to add whitelist entries by UUID and not by name. Because server automatically looks to Mojang.com for UUIDs by the name you wrote. So it will be always online=true UUID. Online UUIDs =/= offline UUIDS.

All you need is to get offline UUID, there are some webpage tools for that, for example our servers have this tool on webpage, : http://tools.glowingmines.eu/ , or you can let the people login and you can see their UUID in console, or they will generate their own player.dat in format of UUID.dat in world folder.

However in offline mode, be sure you have some another thing to protect your server, because any pirated launcher can change name of player, so anybody with the correct name can join. Typical use for that is AuthMe.

Note: you did not wrote your minecraft version, so I assume you use newest or at least NOT TOO OLD one.

Note 2 : Capital letters do NOT matter in UUID generation.

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  • Using offline UUID doesn't works. – Anon May 11 '15 at 3:18
  • I would be cool if people playing in offline mode could customize their UUID directly so they could have their favorite username while keeping UUID in secret for protection. I don't want (and actually can't because my server version is the latest) to install bunch of plugins just to make sure my friends can play with me safely. – Nakilon Jul 8 '17 at 8:33
  • @Nakilon well, from definition, if you use offline mode, your server nor your players are not safe ever. – Antoine Hejlík Jul 27 '17 at 8:14
  • I wished to comment, but it is my first post, so I had to sumbit an answer. (not enogh reputation points) 1. Actually I checked in tools.glowingmines.eu and it seems capital letters DO matter in UUID generation. 2. We still do not know why adding to whitelist on offline servers changes letters case. It seems that is not changed randomly. – Blighthorn Steelmace Sep 10 '17 at 12:35

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