developers.home-assistant/docs/core/platform/raising_exceptions.md

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Raising exceptions

Raising exceptions in service action handlers

Operations like service action calls and entity methods (e.g. Set HVAC Mode) should raise exceptions properly.

Integrations should raise ServiceValidationError (instead of ValueError) in case when the user did something wrong. In this case a stack trace will only be printed at debug level.

For other failures such as a problem communicating with a device, HomeAssistantError should be raised. Note that the exception stack trace will be printed to the log in this case.

Localizing exceptions

Home Assistant supports localization for HomeAssistantError and its subclasses like ServiceValidationError.