I have this error after I restore a backup of my OJS (only code & files):
Fatal error: Call to a member function fetch_array() on a non-object in /home4/oajpc/public_html/pages/index/IndexHandler.inc.php on line 874.
Can anyone help me with this error.
It looks like you have made some extensive customizations to this page.
This error message indicates that the variable you are using to call fetch_array() is not actually an object. This is often the case with a failed instanciation.
We may be able to offer more comments if you can post the specific code section (or better yet, post a link to it on Github, if possible).
The important bit will be how you instanciated $rs in the first line, and whether you are testing for a failure to build the $rs object if an error occurs.