# AUR0011

### **Error message**

Invalid resolver, null/undefined returned from the static register method.

### Error explanation

This error occurs when a static `register` method on a resource or class returns `null` or `undefined` instead of a valid resolver. The DI container expects the `register` method to return a proper resolver object so it can manage the dependency.

### Common causes

* The static `register` method does not return anything or returns `null`/`undefined`.
* There is a bug or missing return statement in a custom resource or plugin's `register` method.
* A plugin or library is not implementing the `register` method correctly.

### How to fix

* Ensure that all static `register` methods return a valid resolver object.
* Double-check custom resources, plugins, or libraries for correct implementation of the `register` method.
* Add appropriate return statements to all `register` methods.

### Debugging tips

* Check the stack trace to see which `register` method caused the error.
* Search your codebase for all static `register` methods and verify their return values.
* If using plugins, try disabling them one at a time to isolate the source.

### Possible solutions

Check the static `register` method on the resource/type referenced in the stack trace, and ensure it returns a valid resolver/registration.

Please also note that this error could be caused by a plugin and not your application. After ruling out that the error is not being caused by your code, try removing any registered plugins one at a time to see if the error resolves itself.