Launcher doesn’t open: Right-click the launcher icon and choose “Run as Administrator.” If not resolved, uninstall it and download the latest version from our website.
Game doesn’t launch: Make sure Java is installed. Try changing the Java version in the launcher settings.
Can’t log in with Microsoft account: Check your internet connection and make sure you’re not using a VPN. Enable TLS 1.2 in your system settings if login fails.
Stuck on loading or black screen: Update your graphics drivers. Open the instance settings and turn off full-screen mode or lower the resolution.
Modpacks won’t install: Make sure you selected the correct mod loader (Forge, Fabric, etc.). If it still fails, delete the modpack instance and try reinstalling it.
Mods not working: Confirm that the mods match the Minecraft version and that the correct loader is installed. Remove any conflicting or outdated mods.
Crashes on startup: Go to the launcher settings and increase the maximum memory. Use a different Java version if the crash log points to a Java issue.
Can’t switch between versions: Check that you’ve installed the version you want from the instance settings. If the version list is empty, refresh the version list in the launcher.
Launcher updates not installing: Download the latest version manually from our website and replace the old launcher file.
Offline mode not working: Double-check the username you entered and ensure there are no extra spaces or symbols. Offline mode doesn’t require a Microsoft account, but it must have a valid player name.
lag or slow performance: Reduce graphics settings in Minecraft, allocate more RAM in its instance settings, and close background apps using too much memory.
Error saying “Java not found” or “Java path incorrect”: Go to instance settings and manually select the correct Java executable.
Linux
Java is missing: You need to install Java to run Minecraft. Open Terminal and type: sudo apt install openjdk-17-jre. Then go into the launcher settings and set the Java path.
Game won’t start: Go into the game’s settings and increase the memory (RAM) if it’s too low. Also, make sure you picked the right mod loader, like Forge or Fabric.
Black screen when the game starts: This might be a graphics issue. Make sure your video drivers are updated. You can also try this command in Terminal to force it to run in safe mode: LIBGL_ALWAYS_SOFTWARE=1 ./UltimMC.AppImage
Can’t log into my account: Make sure your computer’s date and time are correct. If they’re wrong, the login might fail. You can fix this with: timedatectl set-ntp true
Launcher won’t open: Right-click the AppImage file, go to Properties → Permissions, and make sure “Allow executing file as program” is checked. If it still won’t open, try opening it through the Terminal.
Modpacks won’t install: Check that your internet is working. Also, make sure the launcher has permission to save files. If you installed it with sudo, you may need to fix folder.
Game crashes when saving: Make sure your computer isn’t out of storage. Also, don’t run the launcher with sudo; it might block access to your files later.
Launcher crashes or closes quickly: Open Terminal and run the launcher from there to see what the error is. Sometimes a missing library or driver is the cause.
MacOS
Game runs slow: Turn down the video settings inside Minecraft, like render distance or graphics quality. Close other apps to free up your Mac’s memory.
Mods don’t working in the game: Make sure your mod files are in the mods folder for the right Minecraft version you are playing.
Launcher won’t open: Right-click on the UltimMC app and choose “Open.” This lets you run it even if macOS warns you.
Game doesn’t start after clicking Play: Check that you picked the right Minecraft version and installed any needed mods like Forge or Fabric.
Java error: Download Java 17 or Java 8, and run the launcher again.
Can’t download modpacks: Restart the launcher and try again. Check your internet and make sure the Mac’s firewall isn’t blocking the downloads.
Can’t log into your Microsoft account: Check that your Mac’s date and time are correct. If they’re wrong, the login might not work.
Black or white screen after launching the app: This can happen if your Mac’s graphics don’t work well. Try running Minecraft in a smaller window or use a different Java version.
Can’t find your saved games: Open the game instance folder through the launcher and check your saved games.
