You can write something in the chat but it won't be sent?

With me in Minecraft I can unfortunately no longer write anything in the chat no matter which server, single player world. If I open it and write something in there and press enter, nothing happens.

Whenever I join the server, the following comes up in the console. Unfortunately I don't know if that has anything to do with it.

[13:00:51 INFO]: UUID of player Roccat_King is a3c4dbac-5990-4528-9270-9cb7ceb5a6c6

[13:00:51 INFO]: Roccat_King logged in with entity id 30 at ([world] -28.50342031523782, 58.0, 13.500013220621597)

[13:00:53 INFO]: UUID of player Roccat_King is a3c4dbac-5990-4528-9270-9cb7ceb5a6c6

[13:00:53 INFO]: Roccat_King lost connection: You logged in from another location

[13:00:53 INFO]: Roccat_King logged in with entity id 31 at ([world] -28.50342031523782, 58.0, 13.500013220621597)

[13:00:55 INFO]: UUID of player Roccat_King is a3c4dbac-5990-4528-9270-9cb7ceb5a6c6

[13:00:55 INFO]: Roccat_King lost connection: You logged in from another location

[13:00:55 INFO]: Roccat_King logged in with entity id 32 at ([world] -28.50342031523782, 58.0, 13.500013220621597)

[13:00:55 WARN]: handleDisconnection () called twice

[13:01:07 INFO]: Roccat_King lost connection: Disconnected

Hm? How now single player world or server? Both are not possible in one.

If you can't write anything in chat in single player AND on servers, it's up to you.

If you can't write anything in chat on * your * server, it's up to your server.

The console ejects there are just normal join messages and underneath a couple of messages where it says that you wanted to log in with the same account that is already on the server. Probably because you had Minecraft open twice or something. Should have nothing to do with chat

I can't write anything in general. Both in multiplayer and in single player.

Very very weird.

I can't think of a way to turn it on or off, if necessary just save worlds / screenshots / texturepacks and then reinstall

I have already done this several times. Nevertheless, the same mistake always happens.