Fatal Error

When I try to use the plugin I get this error. Any ideas what the problem may be?

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Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /home3/straihi5/public_html/wp-content/plugins/find-and-replace-all/functions.php:55 Stack trace: #0 /home3/straihi5/public_html/wp-content/plugins/find-and-replace-all/frform.php(6): backup_database() #1 /home3/straihi5/public_html/wp-content/plugins/find-and-replace-all/functions.php(37): include(‘/home3/straihi5…’) #2 /home3/straihi5/public_html/wp-includes/class-wp-hook.php(298): fra_display_settings(”) #3 /home3/straihi5/public_html/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters(”, Array) #4 /home3/straihi5/public_html/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #5 /home3/straihi5/public_html/wp-admin/admin.php(222): do_action(‘toplevel_page_f…’) #6 {main} thrown in /home3/straihi5/public_html/wp-content/plugins/find-and-replace-all/functions.php on line 55

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