ThirdReality Smart Plug Gen3 OTA fail (47 to 56)

[markuswinkler]

What happened?

OTA update of a ThirdReality Smart Plug Gen3 (bl702_plug_gen3_usa, hw v1) from firmware 47 to 56 consistently fails with INVALID_IMAGE after the image transfer reaches ~99% complete. The device receives essentially the entire image over Zigbee, then rejects it at the final validation step. This is fully reproducible — every attempt fails the same way.

I have 11 devices of this exact model/hardware revision on my network with the 47 → 56 update pending. I've only attempted the update on one so far (to avoid repeating a failure across all of them), but wanted to flag it before trying the rest.

Log excerpt (Zigbee2MQTT container log):

[2026-08-11 13:47:44] info: z2m:mqtt: ... 'update': {'installed_version':47,'latest_version':56,'progress':98.91,'remaining':17,'state':'updating'} ...
[2026-08-11 13:47:52] error: z2m: OTA update of 'Basement - Dehumidifier - Outlet' failed (OTA update of 0x4ce175b4dc440000 failed with reason: INVALID_IMAGE)
[2026-08-11 13:47:52] info: z2m:mqtt: MQTT publish: topic 'zigbee2mqtt/bridge/response/device/ota_update/update', payload '{"data":{},"error":"OTA update of 'Basement - Dehumidifier - Outlet' failed (OTA update of 0x4ce175b4dc440000 failed with reason: INVALID_IMAGE)","status":"error"}'

Progress climbed steadily and normally right up to the end (0% → 1.91% → 3.88% → ... → 98.91%) before failing — this doesn't look like a stalled or dropped transfer, it completes and is then rejected.

What did you expect to happen?

The device installs firmware 56 successfully.

How to reproduce it

1. Have a ThirdReality Smart Plug Gen3 (USA variant, hw v1) on firmware 47.
2. Trigger the OTA update to 56 (via HA's update.install service or the Z2M frontend).
3. Watch progress climb to ~99%.
4. Update fails with INVALID_IMAGE.

OTA file inspection

I downloaded bl702_plug_gen3_usa_1.00.56.ota directly (same URL Z2M fetches: https://raw.githubusercontent.com/Koenkk/zigbee-OTA/master/images/ThirdReality/bl702_plug_gen3_usa_1.00.56.ota, introduced in #1257) and parsed the ZCL OTA container header to rule out a corrupted/truncated download:

Field	Value	Notes
Magic number	0x0BEEF11E	correct
Header version	0x0100
Header length	60	matches computed offset after optional fields
Field control	0x0004	Hardware Versions Present
Manufacturer code	0x1407 (5127)	ThirdReality
Image type	0xD3BD (54205)
File version	0x00000038 (56)	matches expected latest version
Min/max hardware version	0 / 65520	unrestricted, covers hw v1
Header string	thirdreality
Declared total image size	282386
Actual file size on disk	282386	matches exactly
Sub-element	tag 0x0000 (Upgrade Image), length 282320	60 + 6 + 282320 = 282386 — accounts for every byte, no truncation/trailing data

The outer ZCL OTA container is well-formed and not corrupted or truncated at the wrapper level. I don't have visibility into the BL702-vendor-specific firmware payload inside the Upgrade Image sub-element, so I can't rule out an issue with that inner blob's own integrity check (which is presumably what the device's bootloader is rejecting).

Given the container parses cleanly and the failure is 100% reproducible (not intermittent), a defect in this specific v1.00.56 payload seems more likely to me than transfer-layer corruption over the mesh — but I can't confirm that without BL702's image format spec.

Environment

• Zigbee2MQTT version: 2.13.0-1
• Coordinator: Home Assistant Yellow (EmberZNet/EFR32 radio)
• Device: ThirdReality Smart Plug Gen3, hardware version 1
• IEEE address: 0x4ce175b4dc440000
• OTA file: images/ThirdReality/bl702_plug_gen3_usa_1.00.56.ota (added in update thirdreality plug gen3 to v1.00.56 #1257)

[andrei-lazarov]

cc @3reality-support

[hsugene]

Just adding a +1 here... same ThirdReality devices are failing 47 → 56 with INVALID_IMAGE:

[8/16/2026, 4:08:07 PM] z2m: OTA update of '0x4ce17552b14e0000' failed (OTA update of 0x4ce17552b14e0000 failed with reason: INVALID_IMAGE)

I’m attempting the update directly through Z2M version 2.13.0. Coordinator is a SONOFF Dongle Plus MG24.