SmartThings - SmartThings could not validate the webhook URL

I am having errors with SmartThings’s webhook on Home Assistant Cloud

SmartThings could not validate the webhook URL. Please ensure the webhook URL is reachable from the internet and try again.

Logs:

API error setting up the SmartApp: {‘requestId’: ‘4B0CC8FB-560D-496B-B566-33432540A7CA’, ‘error’: {‘code’: ‘ConstraintViolationError’, ‘message’: ‘The request is malformed.’, ‘details’: [{‘code’: ‘TargetNon200Error’, ‘target’: ‘https://hooks.nabu.casa/MYWEBHOOK’, ‘message’: ‘Target did not respond with a 200 status. Upstream status code=503’, ‘details’: []}]}}
Traceback (most recent call last):
File “/usr/src/homeassistant/homeassistant/components/smartthings/config_flow.py”, line 130, in async_step_pat
app, client = await create_app(self.hass, self.api)
File “/usr/src/homeassistant/homeassistant/components/smartthings/smartapp.py”, line 145, in create_app
app, client = await api.create_app(app)
File “/usr/local/lib/python3.8/site-packages/pysmartthings/smartthings.py”, line 110, in create_app
entity = await self._service.create_app(app.to_data())
File “/usr/local/lib/python3.8/site-packages/pysmartthings/api.py”, line 171, in create_app
return await self.post(API_APPS, data)
File “/usr/local/lib/python3.8/site-packages/pysmartthings/api.py”, line 395, in post
return await self.request(“post”, self._api_base + resource, data=data)
File “/usr/local/lib/python3.8/site-packages/pysmartthings/api.py”, line 368, in request
raise APIResponseError(
pysmartthings.errors.APIResponseError: Unprocessable Entity (422): {“requestId”: “4B0CC8FB-560D-496B-B566-33432540A7CA”, “error”: {“code”: “ConstraintViolationError”, “message”: “The request is malformed.”, “details”: [{“code”: “TargetNon200Error”, “target”: “https://hooks.nabu.casa/MYWEBHOOK”, “message”: “Target did not respond with a 200 status. Upstream status code=503”, “details”: []}]}}

I’m running into the same problem. Have you found any solution for it?