Duplicate temperatureUnit key in /config JSON breaks Home Assistant integration

mandelbrot · March 19, 2026, 4:23pm

I noticed something strange on one of my AirGradient units today. (For context, I have four AirGradient ONE (I-9PSL-DE) units. I have them all connected to the AirGradient dashboard, as well as added on Home Assistant. I’ve been using them this way for several months.)

One of my units stopped reporting data to Home Assistant. I removed it from Home Assistant under Settings > Devices and attempted re-adding it. When I try to re-add it by IP, it says “Unknown error occurred”. When I take a closer look at the Home Assistant logs, it says:

  File "/usr/src/homeassistant/homeassistant/data_entry_flow.py", line 493, in _async_handle_step
    result: _FlowResultT = await getattr(flow, method)(user_input)
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/components/airgradient/config_flow.py", line 108, in async_step_user
    await self.set_configuration_source()
  File "/usr/src/homeassistant/homeassistant/components/airgradient/config_flow.py", line 41, in set_configuration_source
    config = await self.client.get_config()
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/airgradient/airgradient.py", line 109, in get_config
    return Config.from_json(response)
           ~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "<string>", line 39, in __mashumaro_from_json__
mashumaro.exceptions.InvalidFieldValue: Field "temperature_unit" of type TemperatureUnit in Config has invalid value None

It appears to be complaining that Temperature Unit field is set to “None.”

So I went and did curl http://[IP]/config on the problem unit and one of the working units:

Problem unit:

{"country":"US","mqttBrokerUrl":"","httpDomain":"","configurationControl":"cloud","pmStandard":"ugm3","temperatureUnit":"f","disableCloudConnection":false,"postDataToAirGradient":true,"ledBarBrightness":100,"displayBrightness":100,"ledBarMode":"co2","tvocLearningOffset":12,"noxLearningOffset":12,"abcDays":8,"model":"I-9PSL-DE","offlineMode":false,"monitorDisplayCompensatedValues":false,"extendedPmMeasures":false,"temperatureUnit":null}%

Working unit:

{"country":"US","mqttBrokerUrl":"","httpDomain":"","configurationControl":"cloud","pmStandard":"ugm3","temperatureUnit":"f","disableCloudConnection":false,"postDataToAirGradient":true,"ledBarBrightness":100,"displayBrightness":30,"ledBarMode":"off","tvocLearningOffset":12,"noxLearningOffset":12,"abcDays":8,"model":"I-9PSL-DE","offlineMode":false,"monitorDisplayCompensatedValues":false,"extendedPmMeasures":false}%

The problem unit includes two entries for temperatureUnit!

Because temperatureUnit appears twice, the second value (null) apparently overwrites the first ("f"). The Home Assistant AirGradient integration’s parser then rejects the config since None is not a valid TemperatureUnit enum value.

The affected unit is running firmware 3.6.2 on model I-9PSL-DE. All four units are on the same firmware. I’m not sure what triggered the duplicate key on only this one unit. I have tried rebooting the unit and the problem persists. Any ideas?

mandelbrot · March 19, 2026, 4:33pm

Update: A factory reset of the problem unit seems to have fixed it. After the reset, curl http://[IP]/config returns a proper JSON response with a single temperatureUnit key:

{"country":"US","mqttBrokerUrl":"","httpDomain":"","configurationControl":"local","pmStandard":"ugm3","temperatureUnit":"f","disableCloudConnection":false,"postDataToAirGradient":true,"ledBarBrightness":100,"displayBrightness":100,"ledBarMode":"co2","tvocLearningOffset":12,"noxLearningOffset":12,"abcDays":8,"model":"I-9PSL-DE","offlineMode":false,"monitorDisplayCompensatedValues":false,"extendedPmMeasures":false}%

I was then able to re-add it to Home Assistant without issue.

So the root cause was definitely something with the device getting into a bad state with the duplicate key. A factory reset clears it, but it’d still be nice to see the firmware avoid producing duplicate JSON keys in the first place

Tai_AirGradient · March 20, 2026, 8:47am

This finding is valuable. Thank you a lot @mandelbrot !

Could you take a look at whether we can improve this @Samuel_AirGradient ? Thanks!

mandelbrot · March 29, 2026, 2:50pm

Today another one of my AirGradient ONE units starting having this duplicate key issue. (Note, this is a completely different AirGradient ONE unit, and this this time it’s the “pmStandard” key that is duplicated.) As before, this is on firmware 3.6.2.

Here is what I get when I do curl http://[IP]/config on this second problem unit:

{"country":"US","mqttBrokerUrl":"","httpDomain":"","configurationControl":"cloud","pmStandard":"ugm3","temperatureUnit":"f","disableCloudConnection":false,"postDataToAirGradient":true,"ledBarBrightness":100,"displayBrightness":40,"ledBarMode":"off","tvocLearningOffset":12,"noxLearningOffset":12,"abcDays":8,"model":"I-9PSL-DE","offlineMode":false,"monitorDisplayCompensatedValues":false,"extendedPmMeasures":false,"pmStandard":null}%

Note the response includes two entries for pmStandard: "ugm3" and null. As with the first problem unit, it is not communicating with Home Assistant anymore (the fields are all “Unavailable”), though it is communicating just fine with the AirGradient cloud dashboard. The problem persists even if the unit is power-cycled.

For time being, I am leaving this unit in this state, in case there is anything you’d like me to try out on this unit.

MallocArray · March 29, 2026, 3:07pm

Any curl commands you have sent to the unit to set configs that maybe could be resulting in a duplicate key?

mandelbrot · March 29, 2026, 3:11pm

No, I have not sent any other curl commands to the unit.

MallocArray · March 29, 2026, 6:39pm

Any automations you have in HA that could be related? Anything that changes settings?

I don’t think this is super wide spread, so looking to see what is unique in your situation

mandelbrot · March 30, 2026, 1:11am

Nope, no automations in HA related to the AirGradient units, and nothing that would be changing settings from the HA side. They’re just added to HA and logging air quality data so it can be plotted on a dashboard there. I am using the standard, built-in integration for AirGradient. Pretty ordinary setup.

The “Configuration Source” for each device is currently set to “Cloud”. Any custom settings (LED and display brightness) have been set on the AirGradient cloud dashboard under > Edit Location > Monitor Settings. (These settings were set a long time ago, during initial device setup, and haven’t been changed recently.)

mandelbrot · March 31, 2026, 8:35pm

Looks like this same issue has been reported here:

github.com/airgradienthq/arduino

Local configuration has 2 identical temperatureUnit field name

opened 03:15PM - 18 Jun 25 UTC

samuelbles07

## Problem As mentioned in [this issue](https://github.com/home-assistant/core/…issues/144039), there appears to be a case where the same field name, `temperatureUnit`, exists twice in the JSON payload. This results in one of the `temperatureUnit` fields having a `null` value, which causes the [`python-airgradient`](https://github.com/airgradienthq/python-airgradient) library to crash when attempting to parse the configuration. Here is the problematic JSON payload: ```json { "country": "US", "pmStandard": "us-aqi", "ledBarMode": "pm", "abcDays": 8, "tvocLearningOffset": 12, "noxLearningOffset": 12, "mqttBrokerUrl": "", "temperatureUnit": "f", "configurationControl": "cloud", "postDataToAirGradient": true, "ledBarBrightness": 10, "displayBrightness": 20, "offlineMode": false, "model": "I-9PSL", "monitorDisplayCompensatedValues": false, "disableCloudConnection": false, "corrections": { "atmp": { "correctionAlgorithm": "none", "slr": null }, "rhum": { "correctionAlgorithm": "none", "slr": null } }, "httpDomain": "", "temperatureUnit": null } ``` Even though updating `temperatureUnit` locally appears to succeed, when the configuration is retrieved again, the change isn't reflected. Interestingly, the [ArduinoJSON](https://github.com/airgradienthq/arduino/tree/master/src/Libraries/Arduino_JSON) library is able to parse this JSON without issue, which may contribute to the inconsistency. ## Temporary solution There's a quick way to fix this to just factory reset the monitor. But there's a possibility this problem could still occur in the future if the core problem is not fixed.

Tai_AirGradient · April 1, 2026, 1:27am

Hi @mandelbrot, sorry for my late response. And thank you a lot for providing us with comprehensive details.

I’ve checked with our engineer about this issue, and he suggested performing a factory reset (as you mentioned) in the meantime. Although it seems to rarely occur, I’ll discuss with him how we can fix the root cause of this.