Build Error: Missing or Invalid .Target.cs File

What It Means & How to Fix It in UE5

🧠 Why You’re Seeing This Error

This error means Unreal Engine couldn’t find or properly use a .Target.cs file, which tells the engine how to build your game or editor target.

Every UE5 project needs at least one valid target file (usually YourGame.Target.cs and YourGameEditor.Target.cs) to define:

What kind of build it is (Game, Editor, Server, etc.)
Which modules to include
Platform rules and build configurations

If the file is missing, empty, corrupted, or misconfigured — the build fails.

💥 Example Error Message

UnrealBuildTool: ERROR: Target not found. Missing .Target.cs file for 'MyGame'

Or:

UnrealBuildTool Exception: Invalid or missing target rules for MyGameEditor

🛠️ What Usually Causes This

❌ The `.Target.cs` File Doesn’t Exist

You may have deleted or forgotten to create a target file during setup.

❌ The File Exists But Is Empty or Invalid

// ❌ Missing class body or wrong inheritance

❌ You Migrated or Renamed the Project Without Updating Target Files

Changing your project name? You also need to rename your .Target.cs files to match.

❌ You’re Building a Plugin Without a Custom Target (when required)

Some standalone tools or plugin-based projects need their own .Target.cs to build outside the editor.

✅ How to Fix It – Step-by-Step

✔️ 1. Make Sure You Have Valid `.Target.cs` Files

For most projects, you need at least:

Source/
├── MyGame.Target.cs
├── MyGameEditor.Target.cs

✔️ 2. Use a Proper Target File Format

Here’s what a clean .Target.cs file looks like:

// MyGame.Target.cs
public class MyGameTarget : TargetRules
{
    public MyGameTarget(TargetInfo Target) : base(Target)
    {
        Type = TargetType.Game;
        DefaultBuildSettings = BuildSettingsVersion.V2;
        ExtraModuleNames.Add("MyGame");
    }
}

And for the editor:

// MyGameEditor.Target.cs
public class MyGameEditorTarget : TargetRules
{
    public MyGameEditorTarget(TargetInfo Target) : base(Target)
    {
        Type = TargetType.Editor;
        DefaultBuildSettings = BuildSettingsVersion.V2;
        ExtraModuleNames.Add("MyGame");
    }
}

Replace "MyGame" with your actual module name.

✔️ 3. Regenerate Project Files After Creating or Fixing Target Files

Right-click your .uproject → Generate Visual Studio project files

Then rebuild.

✔️ 4. Match Your Target Files to the Project Name

If your .uproject is named EpicShooter.uproject, your target files must be:

EpicShooter.Target.cs
EpicShooterEditor.Target.cs

And the class names inside must match too.

✅ Summary: How to Fix “Missing or Invalid .Target.cs File” in UE5

Cause	Fix Example
No `.Target.cs` file exists	Add valid `MyGame.Target.cs` and `MyGameEditor.Target.cs`
File exists but is invalid	Ensure it inherits `TargetRules` and defines `ExtraModuleNames`
Name mismatch with .uproject	Rename files and classes to match project name exactly
Didn’t regenerate project files	Right-click `.uproject` → Generate project files

UE5 Compilation Errors