ue5-development

name: UE5 Development description: This skill should be used when the user is working in an Unreal Engine 5 project, mentions "UE5", "Unreal", "blueprints", "UnrealBuildTool", "UBT", asks about "editor logs", "build errors", "crash reports", or when a .uproject file is detected in the working directory. Provides knowledge about engine control, log locations, error patterns, and development workflows.

UE5 Development Skill

Specialized knowledge for working with Unreal Engine 5 projects, including engine lifecycle management, log analysis, and debugging workflows.

Detecting UE5 Projects

Identify UE5 projects by checking for:

• .uproject file in current directory or parent directories
• Source/ directory with C++ game code
• Content/ directory with assets
• Saved/ directory with logs and configs

To find the project file:

find . -maxdepth 2 -name "*.uproject" 2>/dev/null | head -1

Engine Installation Paths

Default installation locations by platform:

To detect the engine path, check for user settings in .claude/unreal-engine.local.md first, then fall back to defaults.

Log File Locations

Project Logs (Most Important)

Located in [ProjectRoot]/Saved/Logs/:

• [ProjectName].log - Main editor/game log
• [ProjectName]-backup-*.log - Previous session logs

System Logs by Platform

macOS:

• ~/Library/Logs/Unreal Engine/UnrealEditor/
• ~/Library/Application Support/Epic/UnrealEngine/

Windows:

• %LOCALAPPDATA%\UnrealEngine\5.x\Saved\Logs\
• %APPDATA%\Unreal Engine\

Linux:

• ~/.config/unrealengine/
• ~/.local/share/unrealengine/

Build Logs

UnrealBuildTool output goes to:

• Console output (primary source)
• [ProjectRoot]/Saved/Logs/UnrealBuildTool/

Starting the Editor

macOS

# Find the editor binary
EDITOR="/Users/Shared/Epic Games/UE_5.4/Engine/Binaries/Mac/UnrealEditor.app/Contents/MacOS/UnrealEditor"

# Launch with project
"$EDITOR" "/path/to/Project.uproject"

Windows

# Launch editor
& "C:\Program Files\Epic Games\UE_5.4\Engine\Binaries\Win64\UnrealEditor.exe" "C:\path\to\Project.uproject"

Linux

~/UnrealEngine/Engine/Binaries/Linux/UnrealEditor "/path/to/Project.uproject"

Stopping the Editor

macOS

# Graceful shutdown
pkill -TERM UnrealEditor

# Force kill if needed (wait 5 seconds first)
pkill -9 UnrealEditor

Windows

# Graceful
Stop-Process -Name "UnrealEditor" -ErrorAction SilentlyContinue

# Force
Stop-Process -Name "UnrealEditor" -Force -ErrorAction SilentlyContinue

Linux

pkill -TERM UnrealEditor

Building with UnrealBuildTool

Build Command Structure

# macOS/Linux
"$ENGINE_PATH/Engine/Build/BatchFiles/Mac/Build.sh" \
    [ProjectName][Target] \
    [Platform] \
    [Configuration] \
    -Project="$PROJECT_PATH" \
    -WaitMutex

# Windows
"%ENGINE_PATH%\Engine\Build\BatchFiles\Build.bat" ^
    [ProjectName][Target] ^
    [Platform] ^
    [Configuration] ^
    -Project="%PROJECT_PATH%" ^
    -WaitMutex

Common Targets

Build Configurations

Example Build Commands

# macOS - Build editor
"/Users/Shared/Epic Games/UE_5.4/Engine/Build/BatchFiles/Mac/Build.sh" \
    MyGameEditor Mac Development \
    -Project="/path/to/MyGame.uproject"

# Rebuild (clean + build)
"/Users/Shared/Epic Games/UE_5.4/Engine/Build/BatchFiles/Mac/Build.sh" \
    MyGameEditor Mac Development \
    -Project="/path/to/MyGame.uproject" \
    -Clean

Reading and Analyzing Logs

Tail Recent Logs

# Show last 100 lines and follow
tail -n 100 -f Saved/Logs/*.log

Filter for Errors

# Show only errors and warnings
grep -E "(Error|Warning|Fatal)" Saved/Logs/*.log

Common Error Patterns

Crash Reports

Located in:

• [Project]/Saved/Crashes/
• macOS: ~/Library/Logs/DiagnosticReports/ (look for UnrealEditor*)

Crash logs contain:

• Stack trace
• Loaded modules
• Thread state
• Register values

Development Workflow

Standard Build-Test Cycle

1. Stop editor - Ensure no locks on files
2. Build - Compile changes
3. Start editor - Launch with project
4. Check logs - Monitor for errors

Debugging Build Failures

When a build fails:

1. Read the last 50 lines of build output
2. Look for error: or Error: lines
3. Check if it's a:
   • Compilation error - Fix C++ code
   • Linker error - Check includes/dependencies
   • Blueprint error - Fix in editor
4. Search project source for the error location
5. Fix and rebuild

Debugging Runtime Issues

When the editor crashes or behaves unexpectedly:

1. Check Saved/Logs/[Project].log for recent errors
2. Look for Fatal error or Assertion failed
3. Check crash dumps in Saved/Crashes/
4. Correlate with recent code changes

User Settings

Check for user configuration in .claude/unreal-engine.local.md:

---
engine_path: /custom/path/to/UE_5.4
build_config: Development
platform: Mac
---

Parse with:

# Extract engine_path
grep "^engine_path:" .claude/unreal-engine.local.md | cut -d: -f2- | tr -d ' '

Platform Detection

Detect current platform for cross-platform commands:

case "$(uname -s)" in
    Darwin)  PLATFORM="Mac" ;;
    Linux)   PLATFORM="Linux" ;;
    MINGW*|CYGWIN*|MSYS*) PLATFORM="Win64" ;;
    *)       PLATFORM="Unknown" ;;
esac

Additional Resources

Reference Files

For detailed information, consult:

• references/error-patterns.md - Comprehensive error pattern guide
• references/ubt-flags.md - UnrealBuildTool command-line flags

Scripts

Utility scripts for common operations:

• scripts/detect-project.sh - Find .uproject and engine path
• scripts/parse-settings.sh - Read user configuration