Custom components doesn't work

I installed the latest version of Home Assitant (0.81.5) and I have a problem adding components customization. I have been looking for a topic for a long time and I’m falling on a lack of rights on my files in the folder custom_components but they have all the rights. I do not understand.
I have a file for countdown :

and a file sensor.yaml in directory homeassitant I have :

  • platform: date_countdown
    name: Wedding Countdown
    date: “20-05-2019 18:00”

The answer of configuration.yaml is :
Platform not found: sensor.date_countdown

Thank you for your help

Are you following the directions when adding that custom component? That file needs to be placed in the correct directory. If you are getting platform not found then you haven’t placed the file in the correct directory:

I’m stupid boy, I think the directory need placed in last directory.

I take advantage of having someone competent to know how to use my BME280 on Home Assitant. My sensor is connected directly to the Raspberry PI but following the doc it does not work.

Error while setting up platform bme280

Traceback (most recent call last):
File “/usr/local/lib/python3.6/site-packages/smbus/”, line 81, in open
self._fd =, os.O_RDWR, 0)
FileNotFoundError: [Errno 2] No such file or directory: ‘/dev/i2c-1’

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “/usr/local/lib/python3.6/site-packages/homeassistant/helpers/”, line 128, in _async_setup_platform
SLOW_SETUP_MAX_WAIT, loop=hass.loop)
File “/usr/local/lib/python3.6/asyncio/”, line 358, in wait_for
return fut.result()
File “/usr/local/lib/python3.6/site-packages/homeassistant/components/sensor/”, line 92, in async_setup_platform
bus = smbus.SMBus(config.get(CONF_I2C_BUS))
File “/usr/local/lib/python3.6/site-packages/smbus/”, line 56, in init
File “/usr/local/lib/python3.6/site-packages/smbus/”, line 83, in open
raise IOError(e.errno)
OSError: 2

Could you make it work?
I am encountering a similar problem.