Redirect issues after certain actions

[neurons]

Hi, in a relatively fresh SMF install with few plugins (PrettyURL which is disabled + Auto Twitter + Simple AV Embedder + Stop forum spam + Avatars Display Integration), I've been getting a weird redirect issue, but only in certain locations.

For example I can edit most .css files of a theme directly from SMF admin (cPanel/FTP of course works fine), but I cannot edit index.css of either the default theme or the Boru custom theme, as saving changes redirects to a www-free URL which breaks the cookies and/or session I guess, and logs me out. I was able to edit it this way previously, and I have also tried in the meantime to change the domain from www to without it -> this must be the reason as I can see that

?action=admin;area=theme;th=1;sa=edit

redirects to a non-www URL, even though all settings are handled by www, and theme settings are also setup in www + other css edits work fine, so why is this one failing?

Similarly, when logging in on certain browsers in the 5 secs from page load until I hit login after entering credentials, I get a session expired error, and returned back to login. Here I do not get redirected.

Anything smart to check/rebuild before a fresh reinstall since it's an option?

[neurons]

Second error was due to www/non-www links. Fixed via repair-settings.php, defaulting urls to remove www, and defaulting cookie name: https://wiki.simplemachines.org/smf/Repair_settings.php so should be good now.

First issue is different now - I can successfully hit the save button without getting logged out, however changes aren't actually saved - it returns me to theme root folder without appyling them. Does the same in default theme too.

Latest SMF 2.1.3, PHP 8.2 used.

Incognito modes used on Opera/Chrome/Edge for testing.

[Kindred]

well, if you are in incognito mode --   doesn't that prevent the full admin validation, since that depends on cookies and sessions?

Do you encounter the problem if you use normal mode?

[neurons]

Yep of course, I meant I tested in private mode as well. Weird thing is that it only fails index.css, other css updates fine.

Not a big deal since I update it through cpanel either way, but this got me thinking what other error that's harder to workaround I might face if this isn't working fine?

[live627]

well, if you are in incognito mode --   doesn't that prevent the full admin validation, since that depends on cookies and sessions?

incognito mode never breaks things like that, at least in my experience. It's great for testing things.