'Don't know how to turn "text" into a Component' when trying to chat in a server

This seems to happen only in a server.
There's an error when trying to chat in the server. The servers kicks you with this error message:

Where "Hello Mojang" is the message in chat.
The same happens with some commands. For example: "/effect DanielFerG_ clear" kicks with message "Don't know how to turn "DanielFerG_" into a Component". If I try "/effect DanielFerG_ swiftness", kicks you with "switness". But, "/effect DanielFerG_ 1" works.
Also, "/give DanielFerG_ grass" works, but "/give DanielFerG_ gras" (misspelled) kicks with "gras".