If you are seeing Minecraft Connection lost, Failed to Login Bad Login in Tekkit, then here are the solutions that have helped many fix the issue.

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 Minecraft connection timed out error, normally followed by the phrase "no further information," is often caused by internet connection issues.

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.