You'll never find it... there's no such file.
mdl_config is the name of one of the tables in the database.
Perhaps take a step back and tell us what has gone wrong and what you are trying to do?
thanks a lot and god bless for your prompt reply.......
when i clicked on the link in the error message it redirected me to a moodle debugging screen that said i need to edit the " mdl_config"
please find attached picture of the error message.
thanks so much
Has the installation gone wrong and you've tried to restart it?
To add what Howard asked ...
First line in screen shot is a clue ... "you have an error in SQL syntax ... check the manual ... that ... MariaDB."
So now we know you are using MariaDB.
Your server platform is? PHP version is? MariaDB version is?
Are you installing a moodle inside another moodle code directory? (uhhhh, that's not good)
You might be attempting to install an older version of Moodle on a server
that has higher versions of PHP/MariaDB and thus moodle code is too old.
For a 2.9.x minimum PHP is 5.4.4 and MariaDB is 5.5.31 but that version
of Moodle may not run on PHP 7.0 or 7.1 and MariaDB 10.x.x. (probably won't).
'spirit of sharing', Ken
good evening... and thanks so much for your contribution i greatly appreciate, after reading you debugging suggestion and taking everything into consideration i was able to change my php version on my server from 5.5 to 7.0. everything is working fine now. i was able to install moodle 3.6 and it working perfectly fine. thanks to everyone who contributed. remain blessed