sudo systemctl start php-fpm.service
sudo systemctl enable php-fpm.service
systemctl status php-fpm.service

And now the FOG Web UI is working for me again.

The ?? operator that the error message seemed to be complaining about was apparently introduced in PHP 7. My old CentOS 7.5 server (Eww, I know ) only had PHP 5.6. (Suggesting the install script check the PHP version to make sure it’s at least 7)
I was able to update PHP with the following commands:

sudo yum remove php*
sudo yum install php php-bcmath php-cli php-common php-fpm php-gd php-ldap php-mbstring php-mcrypt php-mysqlnd php-pdo php-pecl-jsonc php-pecl-zip php-process

Doing so replaced the blank white web UI with a message that stated:
“Service Unavailable - The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.”

I then re-ran the sudo ./installfog.sh, and it ran without any problems. The DB schema update step functioned, and I could then login like normal.

However, I don’t think I’m fully out of the woods yet. The install script for some reason messes up the NIS login system, requiring a reboot to make work again, but after the reboot the FOG Web UI is back to showing “Service Unavailable”. I’m suspecting a user permission problem that I need to dig into next (Maybe I should make this a new topic if I need help).

The www-error.log file is full of messages like this:

[05-Feb-2025 08:27:03 America/Toronto] PHP Parse error:  syntax error, unexpected '?' in /var/www/html/fog/lib/fog/fogbase.class.php on line 2594
[05-Feb-2025 08:27:03 America/Toronto] PHP Parse error:  syntax error, unexpected '?' in /var/www/html/fog/lib/fog/fogbase.class.php on line 2594
[05-Feb-2025 08:27:03 America/Toronto] PHP Parse error:  syntax error, unexpected '?' in /var/www/html/fog/lib/fog/fogbase.class.php on line 2594
[05-Feb-2025 08:27:03 America/Toronto] PHP Parse error:  syntax error, unexpected '?' in /var/www/html/fog/lib/fog/fogbase.class.php on line 2594

The same message over and over. They even appears when I’m not trying to access the web UI.

I had a look at the file mentioned in the error log, and that line looks like its setting and “authorized” flag:

$authorized = self::$FOGUser->isValid() ||
  strtolower(($_SERVER['HTTP_X_REQUESTED_WITH'] ?? '')) == 'xmlhttprequest';

This made me wonder if old cookies or other site data in my browser was messing it up. So I cleared my cookies and cache and other browser data. No help.

I’m only kidding. While CentOS 7 is no longer supported and I would (also) suggest moving a a newer OS at this point this isn’t really an issue. Sorry strange mood for me this morning (for me).

Can you give us the output of your /var/log/php-fpm/www-error.log file? This likely is where the actual errors are showing and we can help provide more information.