Fatal error: Uncaught Error: Call to undefined function perform_solr_server_search() in /var/www/app/wp-content/themes/mh-bookshop/functions.php:150
Stack trace:
#0 /var/www/app/wp-includes/class-wp-hook.php(341): replace_with_solr_results(Object(WP_Query))
#1 /var/www/app/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters(NULL, Array)
#2 /var/www/app/wp-includes/plugin.php(570): WP_Hook->do_action(Array)
#3 /var/www/app/wp-includes/class-wp-query.php(1910): do_action_ref_array('pre_get_posts', Array)
#4 /var/www/app/wp-includes/class-wp-query.php(3958): WP_Query->get_posts()
#5 /var/www/app/wp-includes/class-wp.php(704): WP_Query->query(Array)
#6 /var/www/app/wp-includes/class-wp.php(824): WP->query_posts()
#7 /var/www/app/wp-includes/functions.php(1343): WP->main('')
#8 /var/www/app/wp-blog-header.php(16): wp()
#9 /var/www/app/index.php(17): require('/var/www/app/wp...')
#10 {main}
  thrown in /var/www/app/wp-content/themes/mh-bookshop/functions.php on line 150