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Troubleshooting

This page lists common errors you might encounter when using VContainer and how to resolve them.

Common Exceptions​

VContainerException: No such registration of type: X​

Cause: You are trying to Resolve<X>() (or inject X into a constructor), but X has not been registered in the current LifetimeScope or any of its parents.

Solution:

  1. Check your Configure method in LifetimeScope. Ensure builder.Register<X>(...) exists.
  2. If X is an interface, ensure you registered it as that interface: builder.Register<XImpl>(...).As<X>().
  3. If you expect it to be inherited from a parent scope, verify the parent-child connection in the Inspector or code.

VContainerException: Circular dependency detected​

Cause: Class A depends on Class B, and Class B depends on Class A. VContainer cannot create either because they require each other to exist first.

class A { public A(B b) {} }
class B { public B(A a) {} }

Solution:

  1. Refactor (Recommended): This usually indicates a design flaw. Extract the shared logic into a third class C, and have both A and B depend on C.
  2. Lazy Injection: If refactoring is impossible, use Lazy<T> or Func<T> to delay resolution. 
    class A { public A(Lazy<B> b) {} }

VContainerException: Implementation type must be a subclass of ...​

Cause: You tried to register a type as an interface it doesn't implement.

// Error if ServiceA does not implement IService
builder.Register<ServiceA>(Lifetime.Singleton).As<IService>();

Solution: Ensure ServiceA implements IService.

Unity Specific Issues​

MonoBehaviour fields are null after Injection​

Cause: Awake() is called before VContainer injects dependencies into MonoBehaviours in the scene.

Solution:

  1. Move your initialization logic to Start(). VContainer injects after Awake but before Start.
  2. Or, implement IInitializable if you are using RegisterEntryPoint.

"Multiple constructors found"​

Cause: The class you are trying to register has multiple constructors, and VContainer doesn't know which one to use.

Solution: Add the [Inject] attribute to the constructor you want VContainer to use.

class MyService
{
    public MyService() {} // Don't use this

    [Inject]
    public MyService(Dependency d) {} // Use this!
}

Performance Issues​

"GC Allocation is high during Resolve"​

Cause: You might be using Lifetime.Transient for heavy objects or frequently resolving objects inside a tight loop (like Update).

Solution:

  1. Use Lifetime.Singleton or Lifetime.Scoped where possible.
  2. Avoid calling Resolve() inside Update(). Resolve once in the constructor/Start and cache the reference.