Identifying the Issue
The Home Assistant Yellow is a powerful hub built on a Raspberry Pi Compute Module 4 with an integrated Zigbee radio. When it stops working, symptoms can include the web UI becoming unreachable, Zigbee devices not responding, automations failing to trigger, or the device refusing to boot entirely. Because the Yellow combines custom hardware with the Home Assistant operating system, troubleshooting may involve both hardware and software checks.
Common Causes
- Compute Module seating issues: If the CM4 isn't properly seated on the carrier board, the Yellow may fail to boot or experience intermittent crashes.
- Power supply problems: An inadequate power supply causes instability, especially under load when running multiple integrations and add-ons. The Yellow needs a stable, high-quality power source.
- eMMC or NVMe storage corruption: Sudden power loss can corrupt the storage, preventing the OS from loading or causing database errors that affect automations and device history.
- Overheating: Without proper heatsink installation or in an enclosed space, the CM4 can throttle performance or shut down to protect itself from thermal damage.
- Zigbee radio configuration issues: The built-in Silicon Labs Zigbee chip may not be properly configured in ZHA, or its firmware may need updating.
- Network configuration changes: Router changes, new DHCP settings, or IP address conflicts can make the Yellow unreachable even when it's running normally.
Step-by-Step Fixes
- Check physical connections: Verify the power supply is firmly connected and the LED indicator is on. Ensure the Ethernet cable is securely plugged in at both ends. Check that the link lights on the Ethernet port are active.
- Verify power supply adequacy: Use the original power supply included with the Yellow. Third-party adapters that don't provide sufficient amperage can cause random reboots and instability. If you've added power-hungry USB devices, consider whether the total power draw exceeds the supply's capacity.
- Check for overheating: If the Yellow shuts down or becomes sluggish after running for a while, check the heatsink installation. The thermal pad should make full contact between the heatsink and the CM4's processor. Ensure the Yellow is in a well-ventilated location and not inside a sealed enclosure.
- Access via IP address: If you can't reach homeassistant.local:8123, log into your router and find the Yellow's IP address in the DHCP client list. Try accessing by IP directly. If the device isn't listed in your router's clients, it may not be booting to the network stage.
- Reseat the Compute Module: Power off the Yellow and disconnect all cables. Carefully remove the CM4 from the carrier board and reseat it, pressing firmly on both connectors until they click into place. Reconnect everything and power on.
- Fix Zigbee radio issues: In the Home Assistant web UI, go to Settings > Devices & Services > ZHA. If the integration shows an error, try reloading it from the three-dot menu. If the radio isn't detected, go to Settings > System > Hardware to verify it appears. A full reboot often resolves radio detection failures.
- Update firmware and software: Navigate to Settings > System > Updates and install any available updates for Home Assistant OS, Core, and Supervisor. Also check for Zigbee radio firmware updates under Hardware settings. Updates frequently include stability fixes for the Yellow's specific hardware.
- Restore from backup: If the system is corrupted beyond simple fixes, you may need to re-flash the OS using the USB recovery procedure described on the Home Assistant Yellow documentation. After re-flashing, restore your configuration from a backup through the onboarding process.
When to Contact Support
Contact Nabu Casa support if the Yellow fails to power on with any power supply, if the Compute Module doesn't boot on the carrier board after reseating, or if you experience persistent hardware errors. Provide details about LED behavior, any HDMI output if you can connect a monitor, and the troubleshooting steps you've already completed. Hardware defects with the carrier board or the built-in Zigbee chip require professional assessment.
Prevention Tips
- Use a UPS or high-quality surge protector to prevent power loss and storage corruption.
- Schedule automatic backups in Settings > System > Backups and store copies on an external USB drive or network share.
- If using an NVMe SSD, prefer it for the system database to reduce wear on eMMC storage.
- Keep the Yellow in a ventilated area and verify the heatsink is properly attached.
- Perform regular updates to benefit from stability improvements and security patches.
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