Common Errors

Common Errors

Could not create Java Virtual Machine

In a 32 bit OS Environment, you can't set MaximumRam(XMX) higher than 1024.

Error: could not open jvm.cfg

Reinstall Java.
if your launcher uses MJava, remove the runtime directory (default: <Your Minecraft Path>/runtime) and download Java through MJava again.

macOS

DockName

You have to set DockName and DockIcon in LaunchOption.
If DockName is empty, you can't click or access the Minecraft window.

Example:

var launchOption = new MLaunchOption
{
    MaximumRamMb = 1024,
    Session = session, 
    DockName = "Minecraft"
};

On macOS Catalina, Minecraft works normally without the above options. but some macOS versions don't work well.

JRE

Old Minecraft versions don't support OpenJDK 11.

Linux

Use Java 8. Old Minecraft versions don't support OpenJDK 11.

To install Java 8, type the following lines in terminal:

sudo apt-get update
sudo apt-get install openjdk-8-jre

To make sure it worked, type java -version. It should return java version "1.8.0_~~~".