# AUR0010

### **Error message**

Attempted to jitRegister an intrinsic type: `yyyy`. Did you forget to add @inject(Key)

### **Parameters**

Intrinsic type name

### Error explanation

This error occurs when the DI container tries to automatically register (jitRegister) a value that is a JavaScript intrinsic type (such as `String`, `Number`, `Boolean`, `Array`, etc.).

This usually happens because TypeScript's `emitDecoratorMetadata` emits these types for constructor parameters, but Aurelia's DI cannot resolve them unless you explicitly tell it how, using the `@inject` decorator.

### Common causes

* You have a constructor parameter of type `string`, `number`, etc., and did not use `@inject`.
* You are relying on TypeScript's metadata to infer dependencies, but intrinsic types are not automatically resolvable.

### How to fix

* Use the `@inject` decorator to specify the correct dependency key for intrinsic types.

  ```ts
  import { inject } from 'aurelia';
  @inject(String)
  class MyClass {
    constructor(myString) {
      this.myString = myString;
    }
  }
  ```
* If you do not intend to inject an intrinsic type, check for accidental usage or misconfiguration.

### Debugging tips

* Check the constructor parameters of the class that triggered the error.
* Look for missing or incorrect `@inject` usage.
* Review the stack trace to find the source of the resolution attempt.