Web bluetooth DOMException: GATT Error: Not supported

Question

I am trying to receive data from my ESP32 via the Web Bluetooth API. The device can connect to the webpage but after starting to listen to notifications I get the following error:

DOMException: GATT Error: Not supported

There is another thread that has a similar question but there is a properties problem. My properties seem to be okay

This is my code:

let filters = [];
filters.push({name: 'Custom device name'});

let options = {};
options.filters = filters;

try {
  const device = await navigator.bluetooth.requestDevice(options);
  const connectedDevice = await device.gatt.connect();
  console.log('Connected');

  const batteryService = await connectedDevice.getPrimaryService('__SERVICE_GUID__');
  const batteryLevelCharacteristic = await batteryService.getCharacteristic('__CHARACTERISTIC_GUID__');

  var properties = batteryLevelCharacteristic.properties;
  console.log(properties);
  if (batteryLevelCharacteristic.properties.notify) {
    batteryLevelCharacteristic.addEventListener(
      "characteristicvaluechanged",
      async (event) => {
        debugger;
        //console.log(`Received value: ${event.target.value}`);
      }
    );
    await batteryLevelCharacteristic.startNotifications();
  }

}
catch(error) {
    console.log(error);
}

First I get the message Connected

Then i get the properties:

authenticatedSignedWrites : false
broadcast : false
indicate : true
notify : true
read : true
reliableWrite : false
writableAuxiliaries : false
write : true
writeWithoutResponse : false

So Notify is set to true.

At the end I go into the Catch with the error: DOMException: GATT Error: Not supported.

Please let me know if I missed important information

score 0 · Answer 1 · answered Jan 25 '23 at 18:18

Add needed services to filters or optionalServices if a device does not advertise that service to enable access.

let options = {
  filters: [
    { services: ['__SERVICE_GUID__'] },
    { name: 'Custom device name' }
  ],
  optionalServices: ['__SERVICE_GUID__'],
};

Web bluetooth DOMException: GATT Error: Not supported

1 Answers1