What does this mean?

This pops up at in place of the chat box in certain channels all in different servers and it won't let me type.

Some channels it let's me type and open the chat box, and in others this is what it says. Why?

This pops up at in place of the chat box in certain channels all in different servers and it won't let me type.

Some channels it let's me type and open the chat box, and in others this is what it says. Why?