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Publishing & Deployment Issues Oct 26, 2025

Unity Build Fails with "Out of Memory" Error - How to Fix

Fix Unity build failures caused by out of memory errors. Complete solution guide with 8 proven methods to resolve memory issues during compilation and build process.

By GamineAI Team

Unity Build Fails with "Out of Memory" Error - How to Fix

Quick Fix Summary

Problem: Unity build fails with "Out of Memory" error during compilation or build process.

Solution: Increase system memory allocation, optimize project settings, and use build optimization techniques.

Time to Fix: 5-15 minutes

What Causes Unity Build Memory Errors?

Unity build memory errors occur when your system runs out of available RAM during the build process. This typically happens when:

  • Large projects with many assets and scripts
  • Insufficient system RAM for the build process
  • Memory leaks in scripts or assets
  • Inefficient build settings consuming too much memory
  • Background processes competing for system resources

Method 1: Increase Unity Memory Allocation (Recommended)

Step 1: Close Unnecessary Applications

  1. Close all other applications (browsers, editors, games)
  2. End background processes in Task Manager
  3. Free up system RAM before building

Step 2: Increase Unity Memory Limit

  1. Open Unity Hub
  2. Go to Installs → Select your Unity version
  3. Click the gear icon → Add Modules
  4. Add Visual Studio if not already installed
  5. Restart Unity with more memory available

Step 3: Use 64-bit Unity

  • Ensure you're using Unity 64-bit (not 32-bit)
  • Check Unity version in Help → About Unity
  • Download 64-bit version if needed

Method 2: Optimize Build Settings

Step 1: Reduce Build Size

  1. Open Build Settings (File → Build Settings)
  2. Select target platform (PC, Mac, Linux)
  3. Click Player Settings
  4. Go to Publishing Settings
  5. Enable "Strip Engine Code"
  6. Disable "Development Build" for release builds

Step 2: Optimize Scripting Backend

  1. In Player Settings → Configuration
  2. Set Scripting Backend to IL2CPP (if not already)
  3. Set Target Architecture to x64 (64-bit)
  4. Enable "Managed Stripping Level" to High

Step 3: Reduce Texture Quality

  1. Go to Player Settings → XR Settings
  2. Set Texture Quality to Half Res or Quarter Res
  3. Enable "Compress Textures"
  4. Set Texture Compression to High Quality

Method 3: Clean Project and Rebuild

Step 1: Clear Unity Cache

  1. Close Unity completely
  2. Delete the Library folder in your project
  3. Delete the Temp folder in your project
  4. Restart Unity (it will rebuild the Library)

Step 2: Clear Build Cache

  1. Go to Edit → Preferences → External Tools
  2. Clear Build Cache if available
  3. Delete Build folder in your project
  4. Try building again

Step 3: Reimport Assets

  1. Select all assets in Project window
  2. Right-click → Reimport
  3. Wait for reimport to complete
  4. Try building again

Method 4: Optimize Project Assets

Step 1: Reduce Asset Sizes

  1. Compress textures to appropriate sizes
  2. Remove unused assets from the project
  3. Optimize 3D models (reduce polygon count)
  4. Compress audio files to appropriate bitrates

Step 2: Use Asset Bundles

  1. Create Asset Bundles for large assets
  2. Load assets dynamically instead of including in build
  3. Use Addressables for better memory management

Step 3: Optimize Scripts

  1. Remove unused scripts from the project
  2. Optimize script compilation settings
  3. Use IL2CPP for better memory management

Method 5: System Memory Optimization

Step 1: Increase Virtual Memory

  1. Open System Properties (Windows)
  2. Go to Advanced → Performance Settings
  3. Click Advanced → Virtual Memory
  4. Set custom size to 2x your RAM (e.g., 32GB for 16GB RAM)
  5. Restart computer

Step 2: Close Background Processes

  1. Open Task Manager (Ctrl+Shift+Esc)
  2. End unnecessary processes:
    • Browser tabs
    • Other Unity instances
    • Unused applications
    • Background services

Step 3: Use SSD Storage

  • Store project on SSD for faster access
  • Use fast storage for build output
  • Avoid network drives for build process

Method 6: Advanced Build Optimization

Step 1: Use Incremental Builds

  1. Enable "Incremental Build" in Build Settings
  2. Use "Build and Run" instead of "Build"
  3. Only rebuild changed assets

Step 2: Optimize Compilation

  1. Go to Edit → Project Settings → Player
  2. Set "Scripting Define Symbols" to remove unused code
  3. Use "Assembly Definition Files" for better compilation

Step 3: Use Build Profiles

  1. Create different build profiles for different platforms
  2. Optimize each profile for specific needs
  3. Use "Development Build" only when needed

Method 7: Memory Monitoring and Debugging

Step 1: Monitor Memory Usage

  1. Open Unity Profiler (Window → Analysis → Profiler)
  2. Monitor memory usage during build
  3. Identify memory spikes and optimize

Step 2: Use Memory Profiler

  1. Install Memory Profiler package from Package Manager
  2. Analyze memory allocation during build
  3. Find memory leaks and fix them

Step 3: Debug Build Process

  1. Enable "Development Build" for debugging
  2. Use "Script Debugging" to identify issues
  3. Check Console for memory-related errors

Method 8: Alternative Solutions

Step 1: Use Cloud Build

  1. Set up Unity Cloud Build for remote building
  2. Use cloud resources for large builds
  3. Avoid local memory limitations

Step 2: Split Build Process

  1. Build in smaller chunks if possible
  2. Use modular build system for large projects
  3. Build different platforms separately

Step 3: Upgrade Hardware

  • Add more RAM to your system
  • Use faster storage (NVMe SSD)
  • Upgrade CPU for faster compilation

Prevention Tips

Best Practices

  1. Regular project cleanup - remove unused assets
  2. Optimize assets before adding to project
  3. Use version control to track changes
  4. Monitor memory usage regularly
  5. Keep Unity updated to latest stable version

Project Organization

  1. Organize assets in logical folders
  2. Use prefabs for repeated objects
  3. Optimize textures and models
  4. Remove unused scripts and components
  5. Use Asset Bundles for large assets

Common Error Messages

"Out of Memory" During Build

  • Cause: Insufficient RAM for build process
  • Solution: Increase system memory or optimize project

"Build Failed - Memory Allocation Error"

  • Cause: Unity can't allocate enough memory
  • Solution: Close other applications, increase virtual memory

"Compilation Failed - Out of Memory"

  • Cause: Script compilation uses too much memory
  • Solution: Optimize scripts, use IL2CPP, reduce project size

Troubleshooting Checklist

Before Building

  • [ ] Close all unnecessary applications
  • [ ] Check available system RAM (8GB+ recommended)
  • [ ] Ensure Unity is 64-bit version
  • [ ] Clear Unity cache and temp files
  • [ ] Optimize project assets and settings

During Build

  • [ ] Monitor memory usage in Task Manager
  • [ ] Use Unity Profiler to identify issues
  • [ ] Check Console for error messages
  • [ ] Try incremental builds if possible

After Build

  • [ ] Verify build output is correct
  • [ ] Test build on target platform
  • [ ] Check for missing assets or scripts
  • [ ] Optimize for future builds

When to Seek Professional Help

Contact Unity Support if:

  • All methods fail to resolve the issue
  • Error persists after hardware upgrades
  • Build fails on multiple systems
  • Memory errors occur in Unity Editor

Consider professional services for:

  • Large enterprise projects
  • Complex build pipelines
  • Custom build automation
  • Performance optimization consulting

Related Solutions

Summary

Unity build memory errors can be frustrating, but they're usually solvable with the right approach. Start with the quick fixes (closing applications, optimizing settings), then move to more advanced solutions if needed. Remember to monitor your system resources and keep your project optimized for the best build experience.

Need more help? Join our Discord community or check out our Unity troubleshooting guide for additional support.

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