Ticket #54877: 54877.patch

src/wp-includes/wp-db.php

@@ -1892 +1892 @@
                         }
                 }
 
+                // MySQLi port cannot be a string; must be null or an integer.
+                $port = $port ? absint( $port ) : null;
+
                 return array( $host, $port, $socket, $is_ipv6 );
         }