I know you mentioned that you checked the Apache modules but can you check this solution here maybe you overlooked one of them? Also do you have any Virtual hosts? I once had a similar issue with them.
call to undefined function mysql_connect
Multisite Dashboard Always Redirects to Main Dashboard
Problem solved. WordPress had an old version. XAMPP had PHP 8. Incompatible. I uninstalled XAMPP and reinstalled an older version with PHP 7.4. now it’s working fine
Transfer XAMPP local WordPress website from one PC to another
How can I view my site directly from WordPress dashboard?
Xamp installed local wordpress not allowing to publish or install plugin
May be would be helpful for other person in wp-config.php define(‘WP_SITEURL’, ‘http://monurl.site’); define(‘WP_HOME’, ‘http://monurl.site’); It has take a time before changes take effect
The only thing I see as even close to syntactically questionable is that showposts could be replaced with posts_per_page.
$whitelist = array(‘127.0.0.1’); if(!in_array($_SERVER[‘REMOTE_ADDR’], $whitelist)){ // not valid } For more info on how it works. https://stackoverflow.com/questions/1634782/what-is-the-most-accurate-way-to-retrieve-a-users-correct-ip-address-in-php