Issue
Your app is no longer connecting to Redis and you are seeing errors relating to the self signed certificate.
Eg: #<OpenSSL::SSL::SSLError: SSL_connect returned=1 errno=0 state=error: certificate verify failed (self signed certificate in certificate chain)> SSL_connect returned=1 errno=0 state=error: certificate verify failed (self signed certificate in certificate chain)
Resolution
There have been some errors lately in relation to Redis 6 and how it works with self signed certificates. We are currently working on getting our documentation updated to reflect this and make it clearer on how to connect.
With Redis 6 you need to add { verify_mode: OpenSSL::SSL::VERIFY_NONE } (or your language equivalent) in order to get it working. Example implementation for Node, Ruby and Go found here: https://devcenter.heroku.com/articles/securing-heroku-redis#connecting-directly-to-stunnel
For Python apps: By default in python when using Redis, redis-py (used by django-redis-cache) sets ssl_cert_reqs to Required, however this setting must be changed from the default to None. See: https://github.com/andymccurdy/redis-py/#ssl-connections