I use Firefox when visiting the Community. In the past week or so, if I am logged in for more than eight hours (exceeding the standard session time), the next time I refresh the browser, I get a redirect error.
If I open another browser (Chrome), I don't get the error. I have to restart Firefox to access the homepage to log in again.
I get that, too. It seems to happen when I access other Esri sites within the 8 hour window. I don't know enough about OAuth tokens to understand it, but my guess is something's getting mixed up.
Click that ! next to the URL and you can clear your cookies, then refresh. No need to restart the browser.
Thanks for letting us know about this issue and sorry for the inconvenience. The Firefox redirect issue seems to be a bug so we'll raise a support ticket. Expected behavior once you're logged out in an inactive browser/ 8 hour token expiration is to redirect to the Community home page.
For other issues raised relating to accessing other Esri sites during the 8 hour window, there can only be one OAuth token present in the same browser session. If you're logged into one account and then log into another account in the same browser session then the latest account sign in will be the primary and you'll be logged out of your previous one.
If you want to stay logged into Community for 8 hours we recommend opening your Community session incognito or in a different browser to your primary one. That way you can login to a number of different accounts in various browsers and have more than one Oauth token in operation without conflict.