It seems like we have an issue very similar to https://jira.magnolia-cms.com/browse/MGNLSSO-92

DotFusion reports: 

Main concern that @arjuna raised in our call is that Magnolia is still timing out, and you need to clear cache in order to get back in.
For developers this was annoying, but they can deal with it.
But now its designers and content authors trying to use Magnolia to get their jobs done and its extra-annoying because they often need to go to the devs for help to be able to log in again. (Which is not a great feeling.)I guess that this is going to slowly color peoples feeling towards Magnolia.

D&G reports: 

Matt: Do you still experience the issue when you lose connection to Magnolia after some inactivity and need to clean your cookies before being able to log in again?

@josh: Yes, it doesnt seem to reauth. Dont have to clean cookies anymore, just a double page reload sorts it. Sometimes we get a 500 error page. The error page is attached.

mrajkovic COULDN'T reproduce the issue on relatively new subscription kvzjbtwfqvfok9fp. Even after several hours of inactivity, I was able to log back in just fine on Chrome bowser, clean incognito window. 

Additional info

Consolidated additional info from the previous related ticket https://jira.magnolia-cms.com/browse/MGNLSSO-87 by mmichel: 

• We noticed this issue in our own cloud first, and then in the following Okta forum post: https://devforum.okta.com/t/magnolia-sso-single-sign-on-with-okta-too-many-redirects/18031
• Also, the following commit helped to avoid the issue right after logout: https://git.magnolia-cms.com/projects/ENTERPRISE/repos/magnolia-sso/commits/a7698bbf1fe17e361456aac3b8a8d9caa5487d90
• The problem still happened when the Magnolia session expired, thus why we aligned the sessions increasing Magnolia's up to 2 hours.
• Which unfortunately still didn't fix the issue completely.

Next steps

• Asked the DevX team in #saas-try-it-out channel if they reproduced the problem during their two past SaaS testing sessions
• Asked Josh Beckerleg from D&G to look out for the problem
• Asked in #pd-cloud for everyone to look out and ping me if they reproduce it