> 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/0151-to-0179/aur0101.md).

# AUR0101

## Error Message

`AUR0101: Ast eval error: binding behavior "{{name}}" could not be found. Did you forget to register it as a dependency?`

## Description

This error occurs during binding expression evaluation when a binding behavior (used via `& someBehavior`) cannot be found in the current registration scope.

## Solution

* Ensure the binding behavior is registered (globally via `Aurelia.register(...)` or locally via a component’s `dependencies`).
* Check for typos in the behavior name used in the template.

## More Information

This code is also documented under the runtime-html section: [AUR0101](/developer-guides/error-messages/runtime-html/aur0101.md).


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