When I run update.php, I get
PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT filename, name, type, status, schema_version, weight FROM {system} WHERE type = :type; Array ( [:type] => module ) insystem_get_files_database() (line 2188 of/home/content/72/8469872/html/drupal/modules/system/system.module).

What does this mean?