Can't whitelist a player

#1

Hello,
so I have this little server for family and friends and I use whitelist. Now I just can’t add a player named Kacenka in there! I add it like any other player
whitelist add Kacenka
But the game still kicks me out and server says

[20:18:52 INFO]: Disconnecting [email protected][id=fad0079a-ed15-3d95-989a-93fd8e987eb7,name=Kacenka,properties={textures=[com.mojang.aut
[email protected]]},legacy=false] (/myIP): You are not whitelisted on this server!
I then tried
whitelist add fad0079a-ed15-3d95-989a-93fd8e987eb7
but still nothing! That nickname can only connect when whitelist is off. What is the problem?

#2

so I have manually edited whitelist.json and modified UUID. How does the command whitelist add playername know it’s UUID anyway if it’s not online??

#3

Well it queries mojang’s backend to find out what the uuid for that username is.