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In Home Assistant, unknown means no state value is known for the entity. unavailable means the entity cannot provide its state right now. The distinction is useful for troubleshooting, but neither label is a complete diagnosis. An unavailable entity might be powered off, unreachable over the network, connected to a service that is down, or waiting for its integration to finish setting up. An unknown result can also be caused by a misspelled or nonexistent entity ID.
Check the entity’s raw state in Settings > Tools > States, then use the matching diagnostic path. In templates and automations, test whether an entity has a usable value before performing calculations or making decisions.
The two states at a glance
Every Home Assistant entity has one current state value. Typical values include on, off, a temperature such as 21.5, or a person state such as home. Attributes, such as a battery percentage or friendly name, are additional data and are separate from the main state.
| State or case | What it means | First check |
|---|---|---|
unknown |
Home Assistant has no usable state value. A call to states() for an entity ID that does not exist also returns the text unknown. |
Confirm that the entity exists and that its ID is spelled exactly correctly. |
unavailable |
The entity cannot provide a state at this moment. The device, service, or integration may be unreachable or not set up. | Check power, connectivity, integration setup, and system logs. |
has_value('entity_id') is false |
The entity is missing, or its state is unknown or unavailable. |
Branch to an explicit fallback instead of assuming a value. |
Home Assistant’s state-object documentation defines unavailable this way: “The entity cannot provide its state right now.” It gives an unreachable device or service and an integration that has not been set up as examples.
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What unknown means
No state value is known
An entity is unknown when Home Assistant does not have a state value it can use. This does not necessarily identify why the value is missing. The device may not have supplied an initial reading, an integration may not have produced one yet, or a template may have no result to publish.
A missing entity ID can also return unknown
The template function states('entity_id') is deliberately forgiving. If the entity ID does not exist, it returns the string unknown rather than raising an exception. Therefore, seeing unknown in a template does not prove that a real sensor reported an unknown measurement. Check the entity registry and spelling first.
For example, this call returns unknown if the ID is absent:
{{ states('sensor.outdoor_temperatur') }}The typo in outdoor_temperatur is enough to produce that result. Use Settings > Tools > States to copy the exact entity ID instead of typing it from memory.
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Prefer the function form when an entity might be missing
Function syntax is safer than dotted attribute access when an entity may not exist. states('sensor.temperature') returns text, including unknown for a missing ID. By contrast, an expression such as states.sensor.temperature.state can fail when that entity is not present. The function form also makes it easier to test the result before using it.
What unavailable means
The entity cannot provide a state now
unavailable indicates a present inability to provide the state, not a particular root cause. Home Assistant may be unable to reach the physical device, a cloud or local service may be unreachable, or the integration that owns the entity may not have been configured successfully.
Do not interpret every unavailable sensor as proof that its device is offline. A service outage, expired credentials, a failed integration setup, or a temporary startup delay can produce the same label.
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Startup and restored entities
Home Assistant can restore registered entities as unavailable while integrations load. This lets other parts of the system reference the entity immediately, even though the integration has not yet supplied a live value. In this documented restored-entity case, the entity includes a restored attribute. That attribute is a clue about startup or setup timing; it does not mean that every unavailable entity is restored.
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How to diagnose either state
- Open the raw state. Go to Settings > Tools > States, search for the entity, and read the exact state value. A dashboard card may show a friendly name or hide the distinction.
- Verify the entity ID. Compare the ID with the one used in your template, script, or automation. Check domain, spelling, underscores, and device renames. If the ID is absent from the States tool, a
states()call will returnunknown. - For
unknown, identify why no value was produced. Check whether the entity is newly added, whether its integration has completed setup, and whether a template or helper has all of its source entities available. - For
unavailable, check the device or service. Confirm power, batteries, Wi-Fi or Ethernet, and any required hub. For cloud integrations, check the account connection and service status. - Read the logs. Go to Settings > System > Logs. Look for warnings or errors naming the integration, authentication, network connection, or referenced entity.
- Check startup context. If the entity has a
restoredattribute, allow the integration time to load and investigate setup failures if it never receives a live value. - Retest the exact operation. A dashboard refresh, template rendering, or automation trace can show whether the state becomes usable after the underlying issue is corrected.
Templates that handle missing and unusable values safely
Use has_value before displaying a reading
has_value('entity_id') is false when the entity is missing or its state is either unknown or unavailable. It is a good guard when a template needs an actual value:
{% if has_value('sensor.outdoor_temperature') %}
It is {{ states('sensor.outdoor_temperature') }}°C outside.
{% else %}
The outdoor sensor is unavailable.
{% endif %}This check intentionally treats unknown and unavailable alike. If your message or logic must distinguish them, compare the exact state strings:
{% set state = states('sensor.outdoor_temperature') %}
{% if state == 'unknown' %}
No temperature value is known.
{% elif state == 'unavailable' %}
The temperature sensor cannot be reached right now.
{% else %}
It is {{ state }}°C outside.
{% endif %}Convert text to a number only after deciding on a fallback
The return value of states() is text. Arithmetic therefore requires conversion, for example | float. Home Assistant documentation also shows a fallback such as | float(0) to avoid a conversion error:
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For decisions, guard first and choose an explicit unusable path:
{% if has_value('sensor.power') %}
{{ states('sensor.power') | float }} > 100
{% else %}
false
{% endif %}Use a default only when that default is correct for the sensor and the consequence of acting on it is understood.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Automation conditions and triggers
State conditions require exact values
A state condition compares the entity’s state with the value you specify. To test for either special state, enter the exact text unknown or unavailable. An unavailable entity will not pass a condition that expects on, off, or another ordinary value.
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If your goal is to detect any usable state, a template condition using has_value is usually clearer:
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condition:
- condition: template
value_template: "{{ has_value('sensor.outdoor_temperature') }}"Numeric-state conditions stop when values are unusable
A numeric-state condition does not pass while the measured entity is unknown or unavailable. The same applies to an entity used as the threshold. For example, a condition comparing a room temperature with a threshold sensor cannot evaluate if either value is unusable. Check both entities when a numeric condition unexpectedly fails.
Reconnects may not satisfy a prior-state trigger
State-change triggers can require a specific previous state. Suppose a light was unavailable and later reports on. The transition is from unavailable to on, not from off to on. A trigger that explicitly requires off as the prior state therefore will not fire on that reconnection. If reconnection should count, design the trigger and conditions to account for the unavailable-to-live transition.
Common cases and the right first response
A sensor card shows unknown
- Open Tools > States and confirm the entity exists.
- Copy the exact entity ID into the card or template.
- Check whether the integration has produced an initial reading.
- If a template sensor is involved, inspect every source entity it references.
A device entity shows unavailable
- Verify mains power or battery charge.
- Check the device’s network, radio, or hub connection.
- Confirm that the associated service account is connected.
- Read System > Logs for integration errors.
The entity is unavailable only after a restart
Allow integrations to finish loading and inspect the entity’s attributes. A restored attribute indicates the documented restored-entity startup case. If the state remains unavailable, treat it as a setup or connectivity problem and use the logs to identify the failing integration.
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Review both the trigger’s previous-state requirement and every condition. A reconnect may not pass a trigger requiring off, and a numeric condition will not pass until all relevant values are numeric and available.
Quick Recap
A practical checklist
- Read the raw state in Settings > Tools > States.
- Confirm the entity ID exists and is spelled correctly.
- Remember that a missing ID passed to
states()also returnsunknown. - For
unknown, investigate why no value has been produced. - For
unavailable, check power, connectivity, service access, and integration setup. - Inspect Settings > System > Logs for warnings and errors.
- Use
has_valuebefore displaying, converting, or acting on a state. - Use
| float(0)only when substituting zero is safe and intentional. - In automations, account for exact state conditions, unusable numeric values, and reconnect transitions.
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