Fix current issue and upgrading Moodle

We have currently an issue with the version of our Moodle and would like to fix the issue and also upgrading to the latest version of Moodle.

Here are the kind of erreor that we have currently on the main page :
Warning: is_readable(): open_basedir restriction in effect. File(/db/renamedclasses.php) is not within the allowed path(s): (/home/httpd/vhosts/gesformat.ch/:/tmp/) in /home/httpd/vhosts/gesformat.ch/moodle.gesformat.ch/lib/classes/component.php on line 1237 Deprecated: Array and string offset access syntax with curly braces is deprecated in /home/httpd/vhosts/gesformat.ch/moodle.gesformat.ch/lib/weblib.php on line 2976 Deprecated: Array and string offset access syntax with curly braces is deprecated in /home/httpd/vhosts/gesformat.ch/moodle.gesformat.ch/lib/weblib.php on line 2977 Deprecated: Array and string offset access syntax with curly braces is deprecated in /home/httpd/vhosts/gesformat.ch/moodle.gesformat.ch/lib/weblib.php on line 2979 Deprecated: Array and string offset access syntax with curly braces is deprecated in /home/httpd/vhosts/gesformat.ch/moodle.gesformat.ch/lib/moodlelib.php on line 5666