Warning:  [mysql error 2006] MySQL server has gone away

SELECT t.*, count(*) AS counter
  FROM piwikh_image_tag
    INNER JOIN piwikh_tags t ON tag_id = id
  WHERE image_id IN (20921)
  GROUP BY t.id
  ORDER BY NULL in /home/cibermuc/public_html/eltallervalledupar.com/include/dblayer/functions_mysqli.inc.php on line 847

Fatal error: Uncaught Error: Call to a member function fetch_assoc() on bool in /home/cibermuc/public_html/eltallervalledupar.com/include/dblayer/functions_mysqli.inc.php:211 Stack trace: #0 /home/cibermuc/public_html/eltallervalledupar.com/include/functions_tag.inc.php(263): pwg_db_fetch_assoc(false) #1 /home/cibermuc/public_html/eltallervalledupar.com/picture.php(921): get_common_tags(Array, -1) #2 {main} thrown in /home/cibermuc/public_html/eltallervalledupar.com/include/dblayer/functions_mysqli.inc.php on line 211


Warning:  [mysql error 2006] MySQL server has gone away

REPLACE INTO piwikh_sessions
  (id,data,expiration)
  VALUES('12D91dde43b977052c3c133beb4bef035df8','pwg_show_metadata|b:1;pwg_referer_image_id|s:5:\"20921\";',now())
; in /home/cibermuc/public_html/eltallervalledupar.com/include/dblayer/functions_mysqli.inc.php on line 847