I fixed the whole problem right now.
I just opened the config.php and the install.php files and replaced the code on the second line:
‘error_reporting(E_ALL & ~E_NOTICE);
with the following code:
‘error_reporting(E_ALL & ~E_NOTICE & ~E_WARNING & ~E_STRICT & ~E_DEPRECATED);’
There are no warnings again, it works.
Thank you for your support, I appreciate it.