SKLauncher Not Opening Minecraft | Java Version Mismatch

If SKLauncher opens but Minecraft (the game) refuses to start (or crashes immediately after clicking “Play”), it is almost always a “Java Version Mismatch” or a “RAM Allocation” error.

Here is how to fix it, ranked from most likely to least likely.

1. The “Version Rule” (Most Common Fix)

Minecraft requires different Java versions depending on which update you are playing. If you use the wrong one, the game will instantly close (Exit Code 1).

• Minecraft 1.20.5 and newer (inc. 1.21): Requires Java 21.

• Minecraft 1.18 to 1.20.4: Requires Java 17.

• Minecraft 1.16.5 and older: Requires Java 8.

How to fix it in SKLauncher:

1. Right-click the instance (profile) you are trying to play and select Edit.

2. Click More Options.

3. Look at the Java Executable field.

4. If it is set to “Default” or “Autodetect,” try changing it manually to the correct Java path (e.g., if playing 1.21, point it to your Java 21 bin/java.exe file).

   • Tip: If you don’t have the right Java version installed, download it from Adoptium.

Also Read : Unable To Connect to Rockstar Game Services 

2. Fix RAM Allocation

If you allocate too much or too little RAM, the game will fail to initialize.

1. Right-click your profile > Edit > More Options.

2. Look at the Maximum Memory / RAM slider.

3. The Golden Rule: Set it to 4096 MB (4GB).

   • Do not set it to the maximum your PC has (this crashes the system).

   • Do not set it below 2GB (the game won’t start).

3. The “Clean Slate” (Corrupted Assets)

Sometimes the game files downloaded partially or got corrupted. Forcing a re-download usually fixes this.

1. Open SKLauncher.

2. Right-click the profile that isn’t working.

3. Select Open Folder (this opens your .minecraft folder).

4. Delete the folder named bin or natives inside that specific version folder (usually found under .minecraft/versions/[your version]).

5. Go back to the launcher and click Play. It will re-download the missing clean files.

4. Check the Console (Find the Real Error)

If the above didn’t work, you need to see why it’s crashing.

1. Go to SKLauncher Settings.

2. Enable “Show Console” (or “Open Output Log when game starts”).

3. Click Play.

4. Watch the text scrolling by. When it stops/crashes, scroll to the bottom and look for a line that says Caused by: followed by an error.

   • Common Error: java.lang.OutOfMemoryError -> Fix: See Step 2.

   • Common Error: Class has been compiled by a more recent version of the Java Runtime -> Fix: See Step 1 (You need newer Java).

5. Mods Check (If using mods)

If you are trying to launch a Modpack (Fabric/Forge):

• Remove Optifine: It causes many crashes on newer versions. Use Sodium (Fabric) or Embeddium (Forge) instead.

• Delete options.txt: Go to the folder for that version and delete options.txt. This resets video settings that might be crashing your graphics driver.