> For the complete documentation index, see [llms.txt](https://docs.aurelia.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0014.md).

# AUR0014

Key cannot be null or undefined. Are you trying to inject/register something that doesn't exist with DI? A common cause is circular dependency with bundler, did you accidentally introduce circular dep

### **Error message**

Key cannot be null or undefined. Are you trying to inject/register something that doesn't exist with DI? A common cause is circular dependency with bundler, did you accidentally introduce circular dependency into your module graph?

### Error explanation

This error occurs when a `null` or `undefined` key is used in a DI container operation, such as `container.get(key)` or `container.register(key, ...)`. Dependency Injection keys must always be defined and valid.

### Common causes

* A circular dependency or bundler issue (e.g., Webpack) results in a key being `undefined` at runtime.
* A typo or incorrect import leads to a missing or undefined key.
* Attempting to register or resolve a dependency before it is defined.
* Plugins or libraries that incorrectly provide a null/undefined key.

### How to fix

* Ensure all keys used in DI registration and resolution are defined and not null/undefined.
* Check for circular dependencies in your module graph, especially with bundlers.
* Double-check imports and the order of registration.
* If using plugins, ensure they are not introducing null/undefined keys.

### Debugging tips

* Check the stack trace to see where the null/undefined key was used.
* Search your codebase for all registrations and resolutions of the key in question.
* If using a bundler, look for circular dependencies or import issues.
* If using plugins, try disabling them one at a time to isolate the source.


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