RESTful - Invalid HTTP version

Configuration
1

I try to read a JSON file from the integrated Webserver of a B&R PLC.
However I get the following error message in the logger:

Logger: homeassistant.components.rest.data
Quelle: components/rest/data.py:181
Integration: RESTful (Dokumentation, Probleme)
Erstmals aufgetreten: 14:01:29 (2 Vorkommnisse)
Zuletzt protokolliert: 14:01:40

Error fetching data: http://192.168.0.12/indexjson.asp failed with 400, message="Invalid HTTP version:\n\n b'HTTP/3.12.15 Python/3.13 200 OK '\n ^", url='http://192.168.0.12/indexjson.asp'

When I read the file with curl, I get this:

$curl -v http://192.168.0.12/indexjson.asp
*   Trying 192.168.0.12:80...
* Established connection to 192.168.0.12 (192.168.0.12 port 80) from 192.168.1.20 port 43402 
* using HTTP/1.x
> GET /indexjson.asp HTTP/1.1
> Host: 192.168.0.12
> User-Agent: curl/8.16.0
> Accept: */*
> 
* Request completely sent off
< HTTP/1.1 200 OK 
< Date: Wed, 29 Oct 2025 14:04:01 GMT
< Expires: Wed, 29 Oct 2025 14:04:01 GMT
< Server: B&R Web Server  Ver. {2-231112-19}
< Content-Type: text/html; charset=utf-8
< Content-Length: 753
< Connection: close
< 
{
    "tempAussen": 153,
    "tempPufferOben": 565,
    "tempPufferVorlaufHk": 452,
    "tempPufferUnten": 443,
    "betriebsArt": 1,
    "stateHk1": 1,
    "stateHk2": 1,
    "modeHk1": "hkAutomatik",
    "modeHk2": "hkAutomatik",
    "Hk1TempIst": 350,
    "Hk2TempIst": 258,
    "Hk1TempSoll": 347,
    "Hk2TempSoll": 258,
    "anfBrenner": 0,
    "Hk1TempVAus": 240,
    "Hk2TempVAus": 232,
    "Hk1Pumpe": 1,
    "Hk2Pumpe": 1,
    "Hk1MischerZu": 0,
    "Hk1MischerAuf": 0,
    "Hk2MischerZu": 0,
    "Hk2MischerAuf": 0,
    "anfBrennerManuell": 0,
    "reglerHk": {
        "E": 4,
        "P": 320.0,
        "I": 0.0,
        "D": 200.0
    },
    "reglerFbh": {
        "E": -1,
        "P": -100.0,
        "I": 0.0,
        "D": 0.0
    }
}
* shutting down connection #0

What’s the issue?

2

I forgot to mention that the PLC is about 10 years old. So there is definitely no web server with Python 3.13. Don’t know where this version comes from…

3

I’m not sure why you are getting that error, but you could use a command_line sensor instead:

sensor:
  - platform: command_line
    name: custom_json_sensor
    command: "curl -s http://192.168.0.12/indexjson.asp"
    value_template: "{{ value_json }}"
    scan_interval: 60
4

Thanks, I’ll try that

5

You also forgot to share your sensor config.

6

Sorry…
in configuration.yaml:

rest: !include rest_sensors_heizung.yaml

in rest_sensors_heizung.yaml:

- resource: http://192.168.0.12/indexjson.asp
  scan_interval: 60  # alle 60 Sekunden abrufen
  sensor:
    - name: "Außentemperatur"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.tempAussen / 10 }}"
    - name: "Puffer oben"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.tempPufferOben / 10 }}"
    - name: "Puffer Vorlauf HK"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.tempPufferVorlaufHk / 10 }}"
    - name: "Puffer unten"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.tempPufferUnten / 10 }}"
    - name: "Heizkreis 1 Soll"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.Hk1TempSoll / 10 }}"
    - name: "Heizkreis 1 Ist"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.Hk1TempIst / 10 }}"
    - name: "Heizkreis 2 Soll"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.Hk2TempSoll / 10 }}"
    - name: "Heizkreis 2 Ist"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.Hk2TempIst / 10 }}"
    - name: "Betriebsart"
      value_template: "{{ value_json.betriebsArt }}"
    - name: "Regler HK P"
      value_template: "{{ value_json.reglerHk.P }}"
    - name: "Regler FBH E"
      value_template: "{{ value_json.reglerFbh.E }}"
  binary_sensor:
    - name: "Brenner aktiv"
      value_template: "{{ value_json.anfBrenner == 1 }}"
    - name: "HK1 Pumpe"
      value_template: "{{ value_json.Hk1Pumpe == 1 }}"
    - name: "HK2 Pumpe"
      value_template: "{{ value_json.Hk2Pumpe == 1 }}"
    - name: "HK1 Mischer auf"
      value_template: "{{ value_json.Hk1MischerAuf == 1 }}"
    - name: "HK1 Mischer zu"
      value_template: "{{ value_json.Hk1MischerZu == 1 }}"
    - name: "HK2 Mischer auf"
      value_template: "{{ value_json.Hk2MischerAuf == 1 }}"
    - name: "HK2 Mischer zu"
      value_template: "{{ value_json.Hk2MischerZu == 1 }}"
7

Do not get it to work… :frowning:
Could it be a problem that the web server delivers text/html instead of application/json?

8

What changed since it last worked? Have you done a clean shutdown and restart of all the equipment? Twice?

9

Try using the command_line sensor and jq:

sensor:
  - platform: command_line
    name: "heating_raw_json"
    command: "curl -s http://192.168.0.12/indexjson.asp | jq -c '.'"
    value_template: "{{ value_json.tempAussen / 10 }}"
    json_attributes:
      - tempAussen
      - tempPufferOben
      # etc.