To fix Internal Exception: java.io.IOException, An existing connection was forcibly closed by the remote host Minecraft error, you need to follow the given solutions.

The Internal Exception Java.IO.IOException error usually occurs when you launch Minecraft, or when the game is underway. This error can be caused by a number of different things.

How do you fix Minecraft Internal Exception Error (io.netty.handler) (Java.IO.IOException) errors? Simply put, a connection problem causes Minecraft Internal Exception error.