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10 Tech How-To

Lunar Client Keeps Crashing on PC: Fixes

Guide 10-36489 · Updated · Step by step

If Lunar Client keeps crashing on your PC, the fix usually involves updating your graphics drivers, increasing the allocated RAM, or disabling conflicting overlay software. Below are the most effective solutions, ordered from simplest to most advanced, to get you back in-game.

Why Lunar Client Crashes

Lunar Client is a popular Minecraft launcher that bundles mods, cosmetics, and performance tweaks. Crashes can happen for several reasons, but most fall into a few categories: outdated or incompatible graphics drivers, insufficient RAM allocation, corrupted game files, or conflicts with other software like Discord overlays or antivirus programs. Understanding the root cause helps you apply the right fix quickly.

1. Update Your Graphics Drivers

The most common cause of crashes is an outdated GPU driver. Lunar Client uses OpenGL heavily, and old drivers often have bugs that cause the game to crash on launch or during play.

  1. Press Win + X and select Device Manager.
  2. Expand Display adapters, right-click your GPU, and choose Update driver.
  3. Select Search automatically for drivers. If Windows finds nothing, visit your GPU manufacturer’s website (NVIDIA, AMD, Intel) for the latest driver.
  4. Restart your PC and try launching Lunar Client again.

If the crash persists, try a clean driver installation using the manufacturer’s tool (e.g., GeForce Experience or AMD Software) to remove old remnants.

2. Increase Allocated RAM

Lunar Client defaults to a low RAM allocation, which can cause crashes on modded servers or with heavy texture packs. Increasing the memory limit often resolves sudden freezes and crashes.

  1. Open Lunar Client and go to Settings (gear icon).
  2. Navigate to Java or Launcher settings.
  3. Find the Memory slider and set it to at least 4 GB (or 8 GB if you have 16 GB+ of system RAM).
  4. Save and relaunch.

Don’t allocate all your RAM—leave some for your OS and other programs. For example, with 8 GB total, 4 GB is safe; with 16 GB, 8 GB is fine.

3. Disable Overlay Software

Discord, GeForce Experience, and other overlays can interfere with Lunar Client’s rendering, causing crashes. Temporarily disable them to test.

  • Discord: Settings > Overlay > Disable in-game overlay.
  • GeForce Experience: Settings > General > Toggle off In-Game Overlay.
  • OBS or Streamlabs: Close them completely before launching.

If the crash stops, re-enable overlays one by one to find the culprit, then keep it off while playing.

4. Clear Cache and Reinstall

Corrupted cache files can cause crashes. A fresh install often clears these.

  1. Close Lunar Client completely.
  2. Press Win + R, type %appdata%, and hit Enter.
  3. Open the .lunarclient folder and delete the cache subfolder (you can back it up first).
  4. If the problem continues, uninstall Lunar Client via Windows Settings > Apps, then reinstall from the official website.

This resets all settings, so you’ll need to reconfigure your mods and keybinds.

5. Check Java and System Requirements

Lunar Client bundles its own Java, but older PCs may struggle. Ensure your system meets the minimum specs:

  • OS: Windows 10/11 64-bit
  • RAM: 4 GB (8 GB recommended)
  • GPU: Integrated graphics may work, but dedicated is better.

If you have a 32-bit Windows, Lunar Client won’t run. Also, make sure your Windows is up to date, as missing updates can cause compatibility issues.

6. Disable Antivirus or Add Exceptions

Some antivirus programs flag Lunar Client’s mod loader as suspicious, blocking files and causing crashes. Add an exception for the Lunar Client folder.

  1. Open your antivirus settings.
  2. Find the exclusion/exception list (usually under Protection or Settings).
  3. Add the folder where Lunar Client is installed (default: %appdata%\Lunar Client).
  4. Also add the executable file Lunar Client.exe.

If you use Windows Defender, go to Virus & threat protection > Manage settings > Exclusions.

Frequently Asked Questions

Why does Lunar Client crash on launch?

Launch crashes are often due to outdated graphics drivers or insufficient RAM. Try updating your GPU driver and increasing allocated memory to 4 GB as described above.

Does Lunar Client work on Windows 11?

Yes, Lunar Client supports Windows 11. If you’re crashing, ensure you have the latest Windows updates and run the launcher as administrator (right-click > Run as administrator).

How do I fix Lunar Client crashing after an update?

Updates can sometimes corrupt settings. Clear the cache folder (see Section 4) and restart. If that fails, reinstall Lunar Client completely.

Can I use Lunar Client with OptiFine?

Yes, Lunar Client includes OptiFine as a built-in mod. If you’re also installing OptiFine separately, remove the standalone version to avoid conflicts.

Why does Lunar Client use so much RAM?

Lunar Client bundles many mods and features by default, which increases memory usage. Lower the allocated RAM if you’re running out of system memory, but keep it above 2 GB.

Is Lunar Client safe to use?

Yes, Lunar Client is a legitimate launcher used by millions of players. It’s not a cheat client; it’s a performance and cosmetic mod pack. Always download from the official website to avoid malware.

Related

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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