airflow2 migration: upgrade_check - FERNET_KEY issue

[mrc-rius]

I am running the command airflow upgrade_check to do the checks before migrating to Airflow 2.0.

I get the Fernet issue as a problem:

Fernet is enabled by default
The fernet mechanism is enabled by default to increase the security of the default installation.

Problems:
  1.  fernet_key in airflow.cfg must be explicitly set empty as fernet mechanism is enabledby default. This means that the apache-airflow[crypto] extra-packages are always installed.However, this requires that your operating system has libffi-dev installed.

In the airflow.cfg file I have the fernet_key param with a value created using:

from cryptography.fernet import Fernet
fernet_key= Fernet.generate_key()
print(fernet_key.decode())

such as:

fernet_key = dfsnfsjkfsjkfbsjkbfdkjbfs

The problem stills there. I tried setting fernet_key empty, '' and ENV variable value such as:

fernet_key =
fernet_key = ''
fernet_key = {AIRFLOW__CORE__FERNET_KEY} (this one i thing is not correct)

I have installed crypto with pip:

pip install apache-airflow[crypto,postgres,ssh,s3,log]=1.10.14

In the applying the recommendations section in this link from Airflow doc they explain to create a valid fernet_key which is what I did.

Any of these tries do not work and still returns this error.

I run airflow in a docker container. I have an entrypoint script which setups the ENV variables that is really used in the crypto of the database variables.

Any idea in how to fix it, or if i can skip this error if its something knew?