[Help needed] PHP session cookies during login

[agentclark]

Describe the bug
Getting "The web server seems to be incorrectly configured for cookies required for PHP sessions!" during login.

Expected behavior
Access FreshRSS

Environment information Server:

• OS: Debian 11
• FreshRSS version: 1.23.2
• Database version: mariadb Ver 15.1 Distrib 10.5.23-MariaDB
• PHP version: PHP 7.4
• Installation type: git

Environment information Client:

• OS: Windows and Android
• Browser: Firefox, Edge, Chrome, Kiwi

Additional context
I was running FreshRSS smoothly for a couple of years now. Yesterday I did a long due update from 1.21.1 to 1.23.2. Since then I am unable to login on all my devices except for one. On the one device I still can login, I can only login via Firefox and no other Browser.

Before the update I hadn't touched my apache configuration. I now switched from prefork to event with no solution to the problem. FreshRss is running as a subdomain, so no reverse proxy is involved. I tried session.php as mentioned in 5973 and it is counting as expected.

In the apache access log I get a 403 and nothing in error log.
FreshRSS shows [Wed, 13 Mar 2024 11:04:12 +0000] [warning] --- Invalid session during login for user=xxx, nonce= in ./data/users/_/log.txt

I've whiped FreshRSS completly, except for the mariadb database (which I really would love to keep for the favorites) and freshly installed from git.

Thank you so much in advance!

edit: Added FreshRSS log