我尝试添加要在文章的XML提要中生成的字段，但出现此错误：
ErrorThe website encountered an unexpected error. Please try again later
Error messagePDOException: SQLSTATE[08004] [1040] Too many connections in lock_may_be_available() (line 192 of.....
当我在Drupal 7中修改某些内容时，我经常会收到此错误。