Quick Summary
The `java.lang.OutOfMemoryError: Java heap space` error in Minecraft indicates that the Java Virtual Machine (JVM) running Minecraft has run out of allocated memory. This means that the game is trying to use more memory than the JVM has been configured to provide, leading to the error.
Common Causes
- Insufficient Allocated RAM: Minecraft, especially with mods or high settings, requires a significant amount of RAM to run smoothly. If the JVM is not allocated enough initial or maximum RAM, it will eventually run out of memory as the game uses it.
- Memory Leak: Occasionally, a bug in Minecraft or one of its mods can cause a memory leak. A memory leak means the software is using memory, but never gives it back when it's finished with it, leading to an eventual exhaustion of available RAM.
- Too Many Mods/Resource Packs: Mods and resource packs add extra content and functionality to Minecraft, increasing its memory footprint. Installing too many or using very high-resolution resource packs can easily surpass the available heap space.
- High Render Distance/Graphics Settings: Higher render distances and graphics settings demand more memory for generating and rendering the game world. These settings can quickly use up allocated RAM, resulting in the error.
Step-by-Step Fixes
Method 1: Increase Allocated RAM Show Steps ↓
For Vanilla Minecraft (using the default launcher):
Open the Minecraft Launcher.
Go to 'Installations'.
Select your desired installation and click the three dots, followed by 'Edit'.
Click 'More Options'.
In the 'JVM Arguments' field, you'll see a line starting with '-Xmx'. This value determines the maximum RAM allocated to Minecraft. The default is usually -Xmx2G (2 Gigabytes). Change this to a higher value, such as -Xmx4G for 4 GB, or -Xmx6G for 6 GB, but never allocate more RAM than your computer physically has available, minus a bit for the operating system.
Save the installation.
Launch Minecraft.
For Modded Minecraft (using a dedicated launcher like CurseForge or MultiMC):
Open the launcher.
Find the settings related to the instance or profile you are using.
Look for an option to adjust Java settings or memory allocation. This may be under 'Java Settings', 'JVM Arguments', or similar.
Adjust the maximum memory allocation (usually represented by -Xmx) as described above.
Save your changes and launch the instance.
Method 2: Reduce Graphics Settings Show Steps ↓
Decrease the render distance in Minecraft's video settings. Experiment with different values; a lower render distance significantly reduces memory usage.
Lower other graphics settings such as mipmap levels, clouds, and particles to further reduce memory consumption.
Consider using the 'Fast' graphics preset if you are having consistent problems.
Method 3: Remove/Update Mods and Resource Packs Show Steps ↓
If you are using mods, try removing them one by one to see if any specific mod(s) are causing the memory leak. Start with mods that are known to be resource-intensive or those that have been recently updated.
Ensure all your mods are compatible with your Minecraft version. Incompatible mods can cause memory leaks and other issues.
If you are using a high-resolution resource pack, try switching to a lower-resolution pack or the default resource pack to see if that resolves the issue.
Make sure your mods are up to date. Older, incompatible versions can cause memory leaks.
Method 4: Restart Minecraft and Your Computer Show Steps ↓
A simple restart can sometimes clear up temporary memory issues. Close Minecraft completely and then reopen it.
Restarting your computer can also clear unnecessary processes and free up RAM that might be contributing to the problem.
Method 5: Update Java Show Steps ↓
Ensure you are using the latest version of Java that is compatible with your Minecraft version. An outdated Java version can sometimes cause memory-related issues.
You can download the latest Java version from the Oracle website or from adoptium.net (Temurin build, recommended for many Minecraft installations).