I have centos7 machine running MariaDB and phpMyAdmin running properly. I set wordpress for testing running on this machine some months ago and everything was running fine, I finished my test and left the server running for other purposes. Today I needed to access the wordpress sandbox on that server again, but I couldn't. I get the http 500 error I mentioned. I extracted a new wordpress folder in /var/www/html with the same result. I confirmed that the database was running fine, and that the apache server is running properly, but I still get the http 500 error. I also tried to enable debug mode in wp-config.php and I don't get any errors there as well.
Where else can I check for errors?
edit:
Here are the error messages in my /var/log/httpd/error_log
[Mon Mar 11 15:59:14.482983 2019] [:error] [pid 21485] [client 10.0.0.140:49559] PHP Warning: Unknown: failed to open stream: Permission denied in Unknown on line 0
[Mon Mar 11 15:59:14.483029 2019] [:error] [pid 21485] [client 10.0.0.140:49559] PHP Fatal error: Unknown: Failed opening required '/var/www/html/wordpress/index.php' (include_path='.:/usr/share/pear:/usr/share/php') in Unknown on line 0