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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsIn Home Assistant, unknown means no usable state value is known for an entity. unavailable means the entity cannot provide its state at that moment. The labels describe the entity’s current state, not the precise cause. A device may be offline, a service may be unreachable, an integration may not be configured, or a referenced entity may not exist.
The distinction matters in dashboards, templates and automations. A missing entity requested with states('entity_id') also produces the text unknown, while an unavailable entity generally exists but cannot report a value. Check the raw state in Home Assistant before changing hardware, rewriting an automation or applying a numeric fallback.
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How Home Assistant represents an entity state
Every Home Assistant entity has one current state value. Ordinary values include on and off for a switch, a number such as 21.5 for a temperature sensor, or home for a person. Attributes such as a battery percentage, friendly name or unit are additional data; they do not replace the entity’s main state.
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| State or case | What it tells you | First check |
|---|---|---|
unknown |
No state value is known. A nonexistent ID requested through states() also returns this text. |
Confirm that the entity exists and that its ID is spelled correctly. |
unavailable |
The entity cannot provide a state right now. | Check device or service connectivity, power, integration setup and logs. |
has_value('entity_id') is false |
The entity is missing, unknown or unavailable. |
Branch to an intentional fallback or a user-facing message. |
Home Assistant’s state-object documentation defines unavailable this way: “The entity cannot provide its state right now. For example, Home Assistant cannot reach the device or service, or the integration of the entity has not been set up.” That wording is intentionally broad; the state alone is not a diagnosis.
What unknown means
An entity is unknown when Home Assistant has no value it can use for the entity’s state. This can happen when an integration has not supplied an initial reading, when a device has not produced a valid value, or when a template or automation references an entity ID that does not exist.
A missing entity can look like an unknown sensor
The template function states('entity_id') is designed to fail safely. If the ID is absent, the function returns the text unknown instead of raising an exception. Therefore, seeing unknown does not prove that a physical sensor reported an unknown measurement. First check spelling, domain and entity existence.
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For example, this request returns unknown if the entity is missing:
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{{ states('sensor.outdoor_temperature') }}By contrast, dotted access such as states.sensor.outdoor_temperature.state can raise an error when the entity is missing. Prefer the function form whenever an entity could have been renamed, removed or conditionally created.
Unknown is not the same as zero or off
Do not treat unknown as a measurement of zero, and do not interpret it as an intentional off state. A power sensor that is unknown has not supplied a usable reading; a light that is off has supplied a definite state. This difference affects both display logic and safety decisions.
What unavailable means
unavailable means the entity cannot provide its state now, even though Home Assistant recognizes the entity. The documented examples include an unreachable device, an unreachable service and an integration that has not been set up. A network outage, a powered-down device, expired credentials, a service interruption or a failed integration initialization can all lead to the same label.
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Unavailable may be temporary
An entity can become available again after a device reconnects or an integration finishes loading. Treat the label as a current condition, not proof of permanent failure. Conversely, repeated or long-lasting unavailability warrants checking power, network access, credentials, integration configuration and logs.
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Restored entities during startup
Home Assistant can restore registered entities as unavailable so other parts of the system can use the entity record while an integration loads. This is a documented startup and setup case, not a rule that applies to every unavailable entity. Inspect the entity’s restored attribute when you suspect this situation. A restored entity can indicate that setup is delayed or has failed, especially after a restart; the integration still has to initialize before a live value appears.
How to diagnose either state
Use the raw entity state rather than relying only on a dashboard card’s friendly label. Follow this sequence:
- Open the state inspector. Go to Settings > Tools > States. Locate the entity and read its exact entity ID, state and attributes.
- Confirm the reference. Compare the ID with the one used in your template or automation. Check the domain, spelling, underscores and any renamed device or entity.
- If the state is
unknown, verify existence. A missing ID passed tostates()deliberately returnsunknown. Look for a renamed, deleted or disabled entity before troubleshooting a physical sensor. - If the state is
unavailable, check the source. Confirm that the device has power, that the local network or remote service is reachable, and that credentials and integration setup are valid. - Read the logs. Go to Settings > System > Logs. Look for warnings or errors from the relevant integration, connection failures, authentication messages and references to entities that no longer exist.
- Consider startup timing. After a restart, inspect whether the entity has a
restoredattribute and whether the integration is still loading or reported a setup failure. - Retest the actual automation path. A dashboard may recover while a template still uses a misspelled ID, and a device may be available while a threshold entity remains unavailable. Check every entity involved in the action.
Safe templates for unusable values
Use has_value before displaying or using a reading
Home Assistant’s has_value test is false when an entity is missing or its state is either unknown or unavailable. It is useful when the template only needs to know whether a usable value exists:
{% if has_value('sensor.outdoor_temperature') %}
It is {{ states('sensor.outdoor_temperature') }}°C outside.
{% else %}
The outdoor sensor is unavailable.
{% endif %}This deliberately groups the two special states. If your message or recovery path must distinguish them, read the state string and compare it explicitly.
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{% set state = states('sensor.outdoor_temperature') %}
{% if state == 'unknown' %}
No temperature value is known, or the entity ID may be missing.
{% elif state == 'unavailable' %}
The temperature entity cannot report right now.
{% else %}
It is {{ state }}°C outside.
{% endif %}Convert text before arithmetic
states('sensor.temperature') returns text, even when the text contains a number. Convert it before calculations:
{{ states('sensor.temperature') | float }}When conversion can fail, a documented pattern is | float(0). That prevents a conversion error by substituting zero. It is not merely neutral error handling: later logic really receives zero. Use it only when zero is an appropriate and safe fallback for that sensor.
{{ states('sensor.temperature') | float(0) }}For a heater, alarm or other safety-sensitive decision, zero can trigger the wrong branch. Prefer an explicit validity check and an unavailable path:
{% if has_value('sensor.temperature') %}
{% set temperature = states('sensor.temperature') | float %}
{% if temperature < 10 %}
Temperature is below the operating limit.
{% endif %}
{% else %}
Do not make a temperature-based decision until the sensor has a value.
{% endif %}How automations treat these states
State conditions require an exact match
A state condition compares the entity’s state to the value you specify. To test for either special state, select or enter that exact string:
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condition:
- condition: state
entity_id: sensor.example
state: "unavailable"An entity in unavailable does not pass a condition expecting on, off or a number. Likewise, a condition for unknown will not match unavailable.
Numeric-state conditions need usable numbers
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: if either the measurement or the threshold has no usable numeric value, the condition cannot be evaluated. Check both sides when a temperature, energy or humidity automation unexpectedly fails.
Unavailable-to-available transitions may skip a trigger
State-change triggers can require a particular prior state. Suppose a trigger requires from: "off" and to: "on". If the device disconnects while off and later reconnects reporting on, the actual transition is unavailable to on, not off to on. The trigger therefore does not fire. Remove or broaden the prior-state requirement only if that behavior is acceptable, and consider handling reconnection separately.
Common mistakes and safer fixes
- Assuming unknown always means a sensor has not reported. Check whether the entity ID exists because
states()usesunknownfor a missing ID. - Assuming unavailable always means the device is offline. Check the service, integration setup, credentials and startup status as well as the device’s network and power.
- Replacing every invalid value with zero. Use
float(0)only when zero has a valid meaning for the decision; otherwise branch onhas_value. - Reading only a dashboard card. Inspect Settings > Tools > States to see the raw state, exact entity ID and attributes.
- Fixing the measured entity but not its threshold. Numeric conditions require both values to be available and numeric.
- Expecting an off-to-on trigger after reconnection. Verify the actual previous state; a reconnect commonly produces
unavailabletoon. - Using dotted template access for optional entities. Use
states('entity_id')so a missing entity yields a controlledunknownresult that your template can handle.
A practical decision path
When an entity looks wrong, classify it before changing anything:
- If the state is a normal value, troubleshoot the value itself or the automation’s comparison.
- If the state is
unknown, verify that the entity exists, then inspect why no value has been supplied. - If the state is
unavailable, check power, connectivity, service availability, integration setup and logs. - If the entity is restored after startup, wait for integration initialization and investigate any setup error rather than treating the restored value as live data.
- If a template or automation still behaves incorrectly, test every referenced entity with
has_valueand inspect the actual transition that occurred.
The key operational rule is simple: unknown says Home Assistant has no state value to use; unavailable says the recognized entity cannot provide one right now. Verify the entity, its integration and its dependencies before choosing a fallback or allowing an automation to act.
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