# AUR0009

### **Error message**

Attempted to jitRegister something that is not a constructor: '`yyyy`'. Did you forget to register this resource?

### **Parameters**

key (any)

### Error explanation

This error occurs when the DI container tries to automatically register (jitRegister) a value that is not a constructor (class or function) or a registry. The container cannot instantiate or resolve such a value, so it throws this error.

### Common causes

* Attempting to resolve a key that is not a class, function, or registry.
* Typo or incorrect value passed to `container.get()` or dependency injection.
* The resource was not registered before being resolved.
* A plugin or library is trying to resolve an unregistered or invalid key.

### How to fix

* Register the key with the container before attempting to resolve it.
* Ensure the key you are resolving is a valid constructor, function, or registry.
* Double-check for typos or incorrect values in your registration and resolution code.
* If using plugins, ensure they are properly configured and registered.

### Debugging tips

* Check the stack trace to see where the resolution was attempted.
* Search your codebase for all registrations and resolutions of the key in question.
* If using plugins, try disabling them one at a time to isolate the source.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0009.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.