My b2evolution Version: Not Entered

Whenever I add a new Post at admin, red error page shown as below message.
Really have no idea, because working good so far.
Now, although the error page shown, but my Post are successfully publish.

An unexpected error has occured!

If this error persits, please report it to the administrator.

Go back to home page

Additional information about this error:

MySQL error!

MySQL server has gone away(Errno=2006)

Your query:

SELECT DISTINCT user_email, user_locale

FROM evo_subscriptions INNER JOIN evo_users ON sub_user_ID = user_ID

WHERE sub_coll_ID = 1

AND sub_items <> 0

AND LENGTH(TRIM(user_email)) > 0
An unexpected error has occured!

If this error persits, please report it to the administrator.

Go back to home page

Additional information about this error:

MySQL error!

MySQL server has gone away(Errno=2006)

Your query: Session::dbsave()

UPDATE evo_sessions SET
sess_data = 'a:1:{s:22:\"ItemList_filters_coll1\";a:2:{i:0;N;i:1;a:30:{s:13:\"filter_preset\";N;s:6:\"ts_min\";N;s:6:\"ts_max\";N;s:14:\"ts_created_max\";N;s:9:\"cat_array\";a:0:{}s:12:\"cat_modifier\";s:0:\"\";s:9:\"cat_focus\";s:4:\"wide\";s:4:\"tags\";N;s:7:\"authors\";N;s:9:\"assignees\";N;s:15:\"author_assignee\";N;s:2:\"lc\";s:3:\"all\";s:8:\"keywords\";N;s:6:\"phrase\";s:3:\"AND\";s:5:\"exact\";i:0;s:7:\"post_ID\";N;s:12:\"post_ID_list\";N;s:10:\"post_title\";N;s:6:\"ymdhms\";N;s:4:\"week\";N;s:10:\"ymdhms_min\";s:0:\"\";s:10:\"ymdhms_max\";s:0:\"\";s:8:\"statuses\";N;s:5:\"types\";N;s:16:\"visibility_array\";a:6:{i:0;s:9:\"published\";i:1;s:9:\"protected\";i:2;s:7:\"private\";i:3;s:5:\"draft\";i:4;s:10:\"deprecated\";i:5;s:10:\"redirected\";}s:7:\"orderby\";s:9:\"datestart\";s:5:\"order\";s:4:\"DESC\";s:4:\"unit\";s:5:\"posts\";s:5:\"posts\";i:20;s:4:\"page\";i:1;}}}',
sess_ipaddress = '115.164.176.198',
sess_key = 'cnG70uA73UPbOSJG96LsUqUKmiqCTNRV',
sess_lastseen = '2009-12-15 16:18:03',
sess_user_ID = 1

WHERE sess_ID = 51412