home-assistant/core · error · HomeAssistantError

Operation mode not supported

Error message

Operation mode not supported

What it means

Raised by the A. O. Smith water heater entity when a service call asks it to switch to an operation mode it does not expose. The entity only accepts modes present in its operation_list, which is built from MODE_AOSMITH_TO_HA (the modes the device itself reports supporting). Any other mode string is rejected before the client call is made.

Source

Thrown at homeassistant/components/aosmith/water_heater.py:137

        return self.device.status.temperature_setpoint_maximum

    @property
    @override
    def current_operation(self) -> str:
        """Return the current operation mode."""
        return MODE_AOSMITH_TO_HA.get(self.device.status.current_mode, STATE_OFF)

    @property
    @override
    def is_away_mode_on(self) -> bool:
        """Return True if away mode is on."""
        return self.device.status.current_mode is AOSmithOperationMode.VACATION

    @override
    async def async_set_operation_mode(self, operation_mode: str) -> None:
        """Set new target operation mode."""
        if operation_mode not in self.operation_list:
            raise HomeAssistantError("Operation mode not supported")

        aosmith_mode = MODE_HA_TO_AOSMITH.get(operation_mode)
        if aosmith_mode is not None:
            await self.client.update_mode(self.junction_id, aosmith_mode)

            await self.coordinator.async_request_refresh()

    @override
    async def async_set_temperature(self, **kwargs: Any) -> None:
        """Set new target temperature."""
        temperature = kwargs.get("temperature")
        if temperature is not None:
            await self.client.update_setpoint(self.junction_id, temperature)

            await self.coordinator.async_request_refresh()

    @override
    async def async_turn_away_mode_on(self) -> None:

View on GitHub (pinned to 58a3fdb3ea)

Solutions

1. Check the entity's current operation_list attribute in Developer Tools > States and use one of those exact strings
2. Update the automation/script/dashboard to use a supported mode (e.g. STATE_OFF, 'electric', 'heat_pump', 'vacation' as exposed)
3. If the mode should be supported, verify the device status/current_mode mapping in MODE_AOSMITH_TO_HA and file an issue with py-aosmith if the mapping is missing

Example fix

# before
action:
  service: water_heater.set_operation_mode
  target: {entity_id: water_heater.my_heater}
  data: {operation_mode: "heat"}
# after - use a mode from the entity's operation_list
action:
  service: water_heater.set_operation_mode
  target: {entity_id: water_heater.my_heater}
  data: {operation_mode: "electric"}

# In HA, read the entity state before acting
state = hass.states.get("water_heater.my_heater")
supported = state.attributes["operation_list"]
if mode not in supported:
    # pick another or notify
    ...

When it happens

Trigger: Calling water_heater.set_operation_mode with a mode (e.g. 'heat_pump' or 'eco') that is not in this entity's operation_list; the list is derived from MODE_AOSMITH_TO_HA and may be narrower than the generic HA water heater modes. Can also happen if a script/automation was written for a different heater model and reused here.

Common situations: Automation or dashboard card hardcodes a mode string; YAML mode name typo; mode supported on one A. O. Smith model but not another; user copies example config from docs for a different device generation.

Related errors

• not_a_water_heater_device
• username_not_normalized
• Error communicating with API: {err}
• Command not found. Exiting sequence
• No application_credentials platform for {domain}

AI-assisted analysis of home-assistant/core@58a3fdb3ea (2026-08-14). Data as JSON: /api/errors/759636691e799a44. Report an issue: GitHub.