One of the most common reasons though is the sudden loss of internet connection or poor bandwidth issue. For some, it can be caused by a bug in the Minecraft launcher or Windows Operating System.

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. Restart your PC Update Minecraft ...

Enabling the Java Native Sandbox option has helped some users clear up their issues related to io.netty.handler and Java.IO.IOException. Press the Windows key (or click the start menu icon) Type ...