Fatal error: Uncaught Error: Call to a member function add_query_var() on string in /var/www/html/wp-includes/class-wp-taxonomy.php:503
Stack trace:
#0 /var/www/html/wp-includes/taxonomy.php(533): WP_Taxonomy->add_rewrite_rules()
#1 /var/www/html/wp-includes/taxonomy.php(63): register_taxonomy('category', 'post', Array)
#2 /var/www/html/wp-settings.php(499): create_initial_taxonomies()
#3 /var/www/html/wp-config.php(138): require_once('/var/www/html/w...')
#4 /var/www/html/wp-load.php(50): require_once('/var/www/html/w...')
#5 /var/www/html/wp-blog-header.php(13): require_once('/var/www/html/w...')
#6 /var/www/html/ms-home-gate.php(13): require('/var/www/html/w...')
#7 /var/www/html/index.php(2): require('/var/www/html/m...')
#8 {main}
  thrown in /var/www/html/wp-includes/class-wp-taxonomy.php on line 503