# Validation HTML Errors

Please see below a reference to each [@aurelia/validation-html](https://github.com/aurelia/aurelia/tree/master/packages/validation-html) package related error with explanations and resources for debugging and solving.

## Validation HTML Errors (4200-4206)

These errors occur when using validation binding behaviors and validation controllers in HTML templates.

* [AUR4200](https://docs.aurelia.io/developer-guides/error-messages/4200-to-4206/aur4200) - Validate binding behavior on invalid binding type
* [AUR4201](https://docs.aurelia.io/developer-guides/error-messages/4200-to-4206/aur4201) - Validate binding behavior extraneous args
* [AUR4202](https://docs.aurelia.io/developer-guides/error-messages/4200-to-4206/aur4202) - Validate binding behavior invalid trigger name
* [AUR4203](https://docs.aurelia.io/developer-guides/error-messages/4200-to-4206/aur4203) - Validate binding behavior invalid controller
* [AUR4204](https://github.com/aurelia/aurelia/blob/master/docs/user-docs/developer-guides/error-messages/4200-to-4206/aur4204.md) - Validate binding behavior invalid binding target
* [AUR4205](https://github.com/aurelia/aurelia/blob/master/docs/user-docs/developer-guides/error-messages/4200-to-4206/aur4205.md) - Validation controller unknown expression
* [AUR4206](https://docs.aurelia.io/developer-guides/error-messages/4200-to-4206/aur4206) - Validation controller unable to parse expression