Issues with updating Firmware on Zooz Zen27


I have several zooz zen27 dimmers (aka Zooz Central Scene Dimmer).

They were all on firmware 1.0. I'm trying to update them and a few have been easy (a few hours). Others freeze anywhere from 5% done to 100% (for 12-24 hours or more)

I went to sleep with the firmware updater at 77%

Right now, I have the built in Device Firmware Updater reporting "Sent last firmware fragment. Waiting on device..." since I woke up. I went to sleep with the firmware updater at 77%

After 8 hours, of that message, I guess it has failed, but I wanted to check to see if anyone has advice before I abort since it took all day yesterday to get to this point.

I don't see any commonality between the devices that fail and others that succeed. The switch closet to the hub fails. The one furthest away succeeded.

Should I try the community App?
I know I'm not doing anything terribly wrong because I have succeed on 3 switches.

Switches are NOT paired with security on.

There is no harm in bailing out while the file is transferring, it is not flashing it as it goes, that does not happen until the entire file is copied to the device.

I would abort, then shut down the hub, pull power for about 10 seconds and reboot. During that time also power cycle the device with the air gap.

If you have any very chatty devices like multi-sensors or power metering plugs you could power them off temporarily (unplug or remove batteries) to avoid slow downs on the mesh.

Then wait a few minutes and try again, usually they will go faster after that song and dance.

It should normally only take 10-15 minutes to transfer the file.

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Also, if not using it already you may want to check out my driver to unlock all the settings especially once you update them: [DRIVER] Zooz ZEN Switches Advanced (and Dimmers)

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Well, I aborted from that screen. Then I went back to check and voila. the update was done.

I'll still power down, wait and reboot to see if that helps at all with the others.

The main reason that I was updating is that these switches report every dimming level as they shut off an turn on. :laughing:

But maybe cutting power to all the zwave devices will be helpful to get the update done more quickly.

Editted. Nope, I read the screen incorrectly.

If the device is not responding anymore it may have completed the update. I think the ZEN27 typically resets itself after updating, so you have to use the z-wave replace feature to join it back to the hub afterwards. You can also just pair it again but it will create a new device entry and leave a ghost node behind.

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I've shut down all my zwave switches. Seems like it is "speeding" along on a switch that failed for me several times.

Does this look "normal"?

The firmware file has 5766 lines of hexidecimal.

My concern is these seqno which I assume mean sequence number.
I would expect that they would go from 0 to 255 twenty-two times (5766/255). But it seems skip some numbers and double up others. For example, highlighted in yellow 198 (two times) followed by seqno: 5

Thats the Z-Wave logs? I dont look at those very often, usually it is not very useful. Not sure how the sequence numbers work exactly, but yeah I would expect it to work as you said.

Also probably was not needed to shut down all the switches, they are not usually sending out messages unless you use them, I was more thinking if you had any sensors or power meters that might be clogging up the mesh a little.


I don’t have many zwave items. But those switches are REALLY chatty when on v1.0 software.

I’m not sure if that was what previously was holding up the firmware updates. But even now, 12 hours later, it is only 81%. But still making progress.