Overview
During a Z-Wave OTA firmware update, the update may fail with the following error:
Error while calling firmwareUpdateOTA: The node did not acknowledge the command (ZW0204)
This error means that the Z-Wave controller sent the OTA start command, but it did not receive the expected radio acknowledgement from the device. This is usually a communication problem. It does not always mean that the firmware file is wrong. The OTA update cannot start because the first update command did not reliably reach the device, or the device was not able to answer.
What ZW0204 means
ZW0204 means:
The controller sent a command to the Z-Wave device.
The controller expected an acknowledgement.
The acknowledgement was not received.
The command was considered failed.
In this case, the failed command is related to starting the OTA firmware update.
Z-Wave JS can also show the same error for other commands if the destination node does not acknowledge the command.
Why this can happen during OTA update
OTA firmware updates need a more stable Z-Wave connection than normal commands. A normal ON/OFF command is small. A firmware update sends many firmware fragments to the device. Because of this, a device may still work for basic control but fail when an OTA update is started.
Most common causes
1. Weak or unstable Z-Wave signal
The device may have weak or unstable RF communication.
Possible reasons:
The device is too far from the controller.
The route to the device is poor.
The device is behind metal.
The device is inside an electrical cabinet.
There is radio interference near the device or controller.
The Z-Wave USB controller is too close to a computer, hub, or USB 3.0 port.
OTA update requires a reliable route. If the connection is unstable, the update may fail before it starts.
2. The device is sleeping
Battery-powered Z-Wave devices sleep to save battery.
If the device is asleep when the OTA update starts, it may not acknowledge the command. Battery-powered devices must be manually woken up before starting the update. In some cases, the device may go back to sleep before the OTA request is completed.
3. The device is busy or restarting
The device may not answer if it is already busy.
This can happen if the device is:
Processing other commands
Being interviewed
Recalculating routes
Restarting
Recovering from a previous failed OTA attempt
Sending reports
Handling many requests from the gateway
Wait until the device and network are stable before retrying the update.
4. Z-Wave network congestion
The OTA request can fail if the Z-Wave network is busy.
Possible causes:
Frequent power reports
Frequent sensor reports
Polling
Automations sending many commands
Device interview running
Route rebuild running
Another OTA update running
Many devices communicating at the same time
During OTA update, it is best to keep the network as quiet as possible.
5. Unstable route through repeaters
A device may not communicate directly with the controller. It may use one or more mains-powered Z-Wave devices as repeaters. If one repeater on the route is offline, overloaded, or poorly positioned, the device may still sometimes respond to normal commands but fail during OTA update. This is because OTA update needs stable communication for a longer time.
6. S2 communication issue
For securely included devices, an S2 communication issue can prevent the command from completing. This may happen if the secure session is expired, delayed, or desynchronized.
Sometimes this can be improved by:
Pinging the node
Restarting Z-Wave JS UI
Power-cycling the device
Waiting for the network to initialize fully
Retrying the OTA update after communication is stable
7. Device firmware problem
In some cases, the device may crash or restart when it receives the firmware update command. This is less common, but it can happen if the device has a firmware issue or if a previous OTA attempt left the device in an unstable state.
Recommended troubleshooting steps
1. Confirm that the device is alive
Before starting the update, check that the device is shown as alive in the gateway.
In Z-Wave JS UI or Home Assistant, check:
Node status
Last seen time
Device interview status
Device availability
Current values and reports
If the device is shown as dead, unavailable, or not interviewed, do not start the OTA update yet. First fix the communication issue.
2. Ping the device
Ping the device several times before retrying the update. The device should respond consistently. If ping fails or only works sometimes, the OTA update could fail. For battery-powered devices, the device may need to be manually woken up before pinging.
3. Check node statistics
In Z-Wave JS UI, check the device statistics.
Look for:
Failed transmissions
Dropped commands
Route changes
Timeouts
Low RSSI
Poor route quality
High background noise
A high number of failed or dropped packets means the connection is not stable enough for OTA update.
4. Check signal strength and route
Check the Z-Wave signal and route quality.
In Z-Wave JS UI, use:
Network Graph
Statistics
Health Check, if available
Last Working Route
If the route is weak or unstable, try to improve it before updating.
Recommended actions:
Move the Z-Wave controller closer to the device, if possible.
Move the device closer to the controller, if possible.
Use a USB extension cable for the Z-Wave USB controller.
Keep the controller away from computers, and metal surfaces.
Add or improve mains-powered Z-Wave repeaters.
Rebuild routes after changing device positions.
5. Wake up battery-powered devices
For battery-powered devices, wake the device manually before starting the OTA update. Use the wake-up procedure from the device manual.
Important:
Start the update immediately after waking the device.
Keep the device awake if the device requires repeated wake-up actions.
Make sure the battery is not low.
If possible, use a new battery before firmware update.
If the device goes back to sleep, the OTA update may fail with ZW0204 or another timeout error.
6. Reduce Z-Wave network traffic
Before starting the update, reduce unnecessary Z-Wave traffic.
Recommended actions:
Stop other OTA updates.
Stop unnecessary polling.
Temporarily disable automations that send many commands.
Avoid running interviews or route rebuilds during the update.
Avoid controlling many Z-Wave devices during the update.
Wait until the Z-Wave network is stable.
A quiet network gives the OTA update a better chance to start and complete successfully.
7. Restart Z-Wave JS UI
Restarting Z-Wave JS UI can clear temporary communication or session issues.
Steps:
Restart the Z-Wave JS UI add-on or service.
Wait until the Z-Wave network is fully initialized.
Wait another 1–2 minutes.
Check that the device is alive.
Ping the device.
Retry the OTA update.
Do not start the OTA update immediately while the network is still initializing.
8. Power-cycle the device
If safe and supported, power-cycle the device.
For mains-powered devices:
Turn off the breaker.
Wait at least 30 seconds.
Turn the breaker back on.
Wait until the device reconnects.
Ping the device.
Retry the update.
For battery-powered devices:
Remove the battery.
Wait at least 30 seconds.
Insert the battery again.
Wake the device.
Retry the update.
9. Confirm the firmware file
ZW0204 is mainly a communication error, but it is still important to confirm that the firmware file is correct.
Check that the firmware file matches:
Exact device model
Hardware version
Region or frequency version
Firmware target
Current firmware path
Correct update file type
Do not use a firmware file intended for another model or hardware revision.
Recommended order before retrying the OTA update
Use this order before starting the firmware update again:
Confirm the device is alive.
Ping the device several times.
Check signal strength and node statistics.
Reduce Z-Wave network traffic.
Wake the device, if battery-powered.
Restart Z-Wave JS UI, if needed.
Power-cycle the device, if safe.
Confirm the firmware file is correct.
Retry the OTA update.
Collecting debug logs
If the update still fails, collect a Z-Wave JS driver log at Debug level. The log should start shortly before the OTA command is sent and continue until the error appears.
The most useful log lines are the ones immediately before:
ZW0204
These lines can show:
Which command was sent
Which route was selected
Transmission attempts
RSSI information
Whether the node replied
Whether the acknowledgement was missing
Whether the device restarted or stopped responding
What to send to support
If you contact support, include:
Device model
Current firmware version
Firmware file used for update
Hardware version, if available
Gateway or controller model
Z-Wave JS UI version
Z-Wave controller type
Inclusion security level, such as None, S0, or S2
Whether the device is mains-powered or battery-powered
Whether the device was awake during the update
Node statistics
Signal strength or Health Check result
Z-Wave JS debug log showing the ZW0204 error
Steps already tested
This information helps identify if the issue is caused by communication, routing, security, device state, or firmware compatibility.
Summary
The error ZW0204 – The node did not acknowledge the command means that the controller sent the OTA start command, but the device did not acknowledge it. This is usually a Z-Wave communication issue, not necessarily a wrong firmware file.
Before retrying the update, check that the device is alive, has stable communication, responds to ping, has a good route, and is awake if battery-powered. If the issue continues, collect a Z-Wave JS driver debug log and send it to support for analysis.