Every time the error message comes in Minecraft?

Every time I try to access the server, the error message comes up.

What kind of server are you trying to connect to? Public, private, local?

Mostly it is due to a faulty configuration of the server. Can you narrow down the problem more precisely?

Best wishes

A server under construction

OK. Does the server run on your computer or with a hoster? Do others also have the problem with the internal error. If possible, please check the server console to see if there's an error.

The console closes directly and on a linux root server

If you want you can write to me on Discord. Then we can take a closer look at the problem. (Have experience with root server)
Feel free to write to me on Discord: Maximilian1021 # 2888

But everyone else can do it

OK. Please try to find out your UUID via https://mcuuid.net and rename it in the folder "world / playerdata" (just put it after the ending .old. Then try to join again. (If you delete it, your items will be lost in the game).

OK

Then don't you have to reload the server?

How do I get that with putty wwen the console is already in the console?

I don't know how you start your server. If it is with screen → CTRL - A -D. Alternatively, open the putty again and connect it again.

Does not work with./start.sh then connects directly to the server again but anyway

Sorry Was on the way. Can you tell me the content of it? And did that work with the player data?