Blank page on myurl/admin - how to troubleshoot?

Hi. I am trying to do a manual install of FreePBX 16 with Asterisk 20.0 (I didn’t realize this would complicate things when I started, and then I was reluctant to go back). I am on Ubuntu 22.04 with PHP 7.4.

I got over a bunch of hurdles until it finally finished installation. Now I go to myurl/admin and I see the browser redirects to myurl/admin/config.php but that’s it, nothing appears, just a white page.

I don’t see anything appearing in php_errors.log. I tried fwconsole debug, I see INFO messages but nothing that appears too serious.

Google gives me a bunch of pages with people facing this issue, but I always get very specific responses like some bug back in 2015 or a missing DB connection which I don’t think is the case with me.

How can I get a more specific notion of what is breaking my new installation? How can I troubleshoot this more methodically?

To be honest, I am not too surprised that my installation doesn’t work, it’s a new one, my first of this kind, and it didn’t go well! :smiley: But I sure would like to see an error message, not just a blank page, to convince me to restart the past 4 hours of work…

Thanks!