Additional uncaught exception thrown while handling exception.
Original
PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT * FROM {uc_product_classes}; Array ( ) in uc_product_class_load() (line 1453 of C:\inetpub\drupal7\sites\all\modules\ubercart\uc_product\uc_product.module).
Additional
PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT ff.* FROM {filter_format} ff WHERE (status = :db_condition_placeholder_0) ORDER BY weight ASC; Array ( [:db_condition_placeholder_0] => 1 ) in filter_formats() (line 427 of C:\inetpub\drupal7\modules\filter\filter.module).
Uncaught exception thrown in session handler.
PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away in _drupal_session_write() (line 209 of C:\inetpub\drupal7\includes\session.inc).
添加内容类型的时候，出现如下错误，我线上服务器是windows环境下，也用过了max_allowed_packet = 32M
你看看这篇文章： https://drupal.org/n
你看看这篇文章：
https://drupal.org/node/1014172
To solve, add in the [mysqld] section in my.ini: max_allowed_packet=100M and restart MySQL
it really is the 256M that does the trick. If I set it to 100M it throws that nasty error.
意思是说，MYSQL的配置，设置的大一点就可以了，这里推荐的是256M，你的只有32M。
另外配置了以后，需要重启MYSQL。