my words, Immanuel :)
see https://github.com/opensource-socialnetwork/opensource-socialnetwork/issues/1749

Why not include the step of checking permissions and ownerships into the installation process?
It's a vital part and not everybody unzips an archive via console and ssh on the hosting server directly.

the first time I ran the installer it went through, before I saw the blank page. So somehow there must have been a different environment afterwards. Unfortunately I have no usable information in the error log. If we can ignore, the better.

compilation error or so ...
Very strange.
If you still remember, of course 'or so' would be of real interest :)

Maybe you entered something this preg_match could not handle?
Allowed entries are either hostnames which would resolve to ips like
localhost or yourhost.com
or simply ips like
187.14.19.34
both in combination with a port number in case it differs from the default port 3306, like
localhost:3310
or
187.14.19.34:3310

yeah sure (sorry about being late)

installation/classes/OssnInstall.php line 192

PHP 7.3 couldn't compile the preg_match command (compilation error or so)
since I would not want to add a different port to the db-hostname I just hardcoded the port to 3306

so I ran this simplified function instead:

public function dbhost($dbhost) {
    if(!empty($dbhost)) {
            $this->dbhost = $dbhost;
    } else {
            $this->dbhost = 'localhost';
    }
    //set the port
    $port = 3306;
    $this->dbport($port);                   

}

Thank you for your feedback, Immanuel.

I'm a little alarmed by your step 3a, though.
Could you please provide the exact warning/error from your error_log file?

Scenario:
I uploaded the unzipped files via ftp into the webdirectory as described in https://www.opensource-socialnetwork.org/wiki/view/706/how-to-install-open-source-social-network

Solution (that worked for me):
1) Sort out all file and directory ownerships and permissions: ownership always webserver, permission of directories 755, permission of files 644, don't forget the data-directory outside the webdirectory
2) Delete all previously created database tables
3) Rerun the installer on DOMAIN/installation/
3a) if you get a php error about preg match compilation, simplify the code in the file accordingly (sorry about that)
4) if you cannot continue, open DOMAIN/installation/?action=finish
5) open DOMAIN/administration/

now checking permissions by help of page https://www.opensource-socialnetwork.org/wiki/view/1101/how-to-report-a-bug-error CASE A