@intg backup Since the community does not seem to have an answer, we wanted to reach out and see if you still require assistance with this matter.
There are a number of reasons why this error can be caused. Below are a few items to review.
With Docker in App Services, SSH needs to be enabled on the image itself, with the SSH server using the credentials username 'root', password 'Docker!' and listening on port 2222, exposed to port 80. Additionally, it's important to be aware that in Docker Compose deployments, only the primary container will be accessible over SSH.
You can also compare/contrast your files to the ones listed here, which is are known working SSH samples for django or python:
Sometimes scaling up your web app, waiting 20-30 minutes, and then scaling back down can also help if SSH falls into a locked state, which is rare but an easy troubleshooting step to try.
Let us know the results of the above suggestions. We look forward to your reply.