Home Assistant Entities

In this tutorial, you'll learn about Home Assistant Entity Issues. We cover key concepts, practical examples, and best practices.

Hook

You look at your Home Assistant dashboard and see "sensor.temperature: Unavailable" or "light.living_room: Unknown." Some entities show as available but never change state. Others appear as duplicates — light.living_room and light.living_room_2.

The Wrong Way

Deleting entities from the Entity Registry without understanding why they became unavailable can break automations and scripts that reference them.

# BAD: Blindly deleting unavailable entities
# Web UI → Settings → Devices & Services → Entities → Delete

Entity deleted
Automation "night_mode" references sensor.temperature — now broken
Automation shows: "Entity not found"

Deleting is permanent. Automations using that entity break silently.

The Right Way

Diagnose why entities become unavailable or duplicate.

# 1. Check the entity state in Developer Tools
# Web UI → Developer Tools → States → Search entity

sensor.temperature:
  state: unavailable
  attributes:
    friendly_name: Temperature
    device_class: temperature

# 2. Check entity registry
curl -s -H "Authorization: Bearer <token>" \
  http://hass.local:8123/api/config/entity_registry/sensor/temperature | jq .

{
  "entity_id": "sensor.temperature",
  "disabled_by": "user",
  ...
}

The entity was disabled by user. Re-enable it:

# Web UI → Settings → Devices & Services → Entities → Find entity → Enable

# 3. Fix duplicate entities
# Two integrations are creating the same entity.
# Disable one integration's entity:
# Web UI → Settings → Devices & Services → Entities → sensor.temperature_2 → Disable

# 4. For stuck entities, reload the integration
# Settings → Devices & Services → Integration → Three dots → Reload

Entity reloaded — state updated
sensor.temperature: 22.5 °C

Prevention

• Use unique IDs in your integrations to prevent duplicates.
• Disable (not delete) entities you do not need — disabling preserves the registry entry.
• Monitor entity states with the history integration to spot anomalies.
• After adding a new device, check the entity registry for duplicates.
• Keep unused entities disabled rather than deleting them; automations will fail gracefully instead of giving errors.

Advanced Troubleshooting

Check the Logs

Most TOOL errors are logged to stdout or a dedicated log file. Check your logs first:

# Check system logs
journalctl -u tool --since "1 hour ago"

# Or check the application log
tail -50 ~/.tool/logs/error.log

Test with a Minimal Example

Create the simplest possible tool configuration to verify the base setup works:

tool --version
tool --help

If the minimal test passes, add configuration options one at a time until you find the breaking change.

Common Configuration Mistakes

• Using the wrong file path or URL in configuration
• Forgetting to restart TOOL after changing config files
• Mixing tabs and spaces in YAML configuration files
• Setting incorrect permissions on configuration directories

When to Reinstall

If none of the above resolves the issue, consider a clean reinstall:

# Backup your configuration
cp -r ~/.tool ~/.tool.bak

# Remove and reinstall
# Follow the official TOOL installation guide

This ensures you start from a known good state and can isolate the issue.

Common Mistakes with assistant entities

1. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks
2. Using return to exit a function early instead of wrapping a pure value in the monad
3. Mixing let bindings with <- bindings in do notation, producing type errors

These mistakes appear frequently in real-world HOME code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

DodaTech — entities that you can count on.