Are you sure redis is working? it sound like that joomla is unable to create a session.

Hi,
I use Redis as session manager and cache in many joomla instances with default parameters.
Eight of them are on the same Redis database, and I have no issue of any kind. In that regard, it is better than memcached.
You should look at your Redis server or the Redis connector, or ask your provider if he can provide details.

Actually i suspect it could not create the session. Which leads to a second possible bug, i keep getting an error "Redis ping failed" however when i run redis-cli from the client machine to the target redis machine, there is no issues at all. I even see joomla sending "Select 0" pings consistently to the redis server. Anyway i can debug what went wrong?

Additionally, it actually worked for a long while, and just suddenly stopped working 2 days ago.

Have you recently added a password for Redis Database 0 ?

Is Redis Database 0 shared between multiple Joomla sites ?

What happens if you use Redis Database 6 for example?

What happens if you clear ALL Cookies in your browser for the site BEFORE loading the login page?

Set to "closed" on behalf of @Quy by The JTracker Application at issues.joomla.org/joomla-cms/22556

This can be reopened when the requested information is provided.