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:

Platform	Default Path
macOS	/Users/Shared/Epic Games/UE_5.x
Windows	C:\Program Files\Epic Games\UE_5.x
Linux	~/UnrealEngine or /opt/UnrealEngine

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

Target	Description
Editor	Build for editor (e.g., MyGameEditor)
Game	Standalone game build
Client	Multiplayer client
Server	Dedicated server

Build Configurations

Config	Use Case
Development	Default, debugging enabled
DebugGame	Full debugging, slower
Shipping	Release, optimized
Test	Testing builds

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

Pattern	Meaning
LogCompile: Error:	C++ compilation error
LogBlueprint: Error:	Blueprint compilation error
LogLinker: Warning:	Asset reference issues
Assertion failed:	Runtime assertion (crash)
Fatal error:	Unrecoverable crash
LogShaderCompiler: Error:	Shader compilation failure
LogAssetRegistry:	Asset loading issues
LogHotReload:	Hot reload/Live Coding issues

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