Common Issues

Common Launcher Issues

1. The game is running. Please wait.
   Unrecognized option: -p
   Error: Could not create the Java Virtual Machine.
   Error: A fatal exception has occurred. Program will exit.
   Process ended with code: 1

   This error means that you are using an incompatible version of Java. See Updating Java on how to update your Java on your machine.

2. The game is running. Please wait.
   Unrecognized VM option 'UseCMSCompactAtFullCollection'
   Error: Could not create the Java Virtual Machine.
   Error: A fatal exception has occurred. Program will exit.
   Process ended with code: 1

   This error means you have the wrong JVM arguments assigned on the MyM launcher. Go to Options -> Java on the launcher and only put in -Djava.net.preferIPv4Stack=true argument in the JVM Arguments section of options removing everything else. This is automatically fixed in newer downloads of the launcher and only happens if you have older downloads of the MyM launcher.

3. sun.security.validator.ValidatorException: PKIX path building failed:
   sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

   This error means that Java cannot validate the Minecraft certificate that it needs to authenticate your Minecraft account. There are a couple of reasons why this can happen. The most common way to fix this is to uninstall all of your Java versions on your computer and re-installing them. You can find installs here. The other issue you might run into is that your anti-virus is blocking the launcher. Make sure that your anti-virus allows the MyM Launcher through your firewall.

The list of modpacks could not be downloaded

• This happens for a few reasons. Usually, it means your firewall is blocking access to the download servers. To allow the application for your firewall, see the guide below.
• If allowing it in your firewall did not fix it, it could also be caused when an application forces Java to use IPv6 instead of IPv4. To fix this, please look in your installed programs for a program called RelevantKnowledge. This application is a known malware that alters internet traffic and causes unwanted behavior. Remove it, and it should fix this issue. If all else fails, see below on how to force java to use IPv4.

Windows 10 Firewall Guide

Forcing Java to use IPv4

1. Open command prompt (windows start button, type cmd in search)
2. Click the top left of command prompt, click properties, enable quick edit mode
3. Copy this command: setx _JAVA_OPTIONS -Djava.net.preferIPv4Stack=true
4. Right-click on command prompt window to paste it and then hit enter.

Please contact staff to report any issues regarding the MyM Launcher.