WSOD with error when login as administration I was working on website and suddenly noticed that a particular page had a error message and lost a lot of css styles.

When I went back to the back-end I saw a white page with following message and nothing else (no administration menu, no content overview, ...

Error message

Additional uncaught exception thrown while handling exception.

Original

PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT s.uid, c.updated FROM {ctools_object_cache} c INNER JOIN {sessions} s ON c.sid = s.sid WHERE s.sid &amp;lt;&amp;gt; :session_id AND c.obj = :obj AND c.name = :name ORDER BY c.updated ASC; Array ( [:session_id] =&amp;gt; HWv-9jPhNMHqjMdxRprJh-YmmBQc2y0jWXrbR_68TeA [:obj] =&amp;gt; view [:name] =&amp;gt; article_4pc ) in ctools_object_cache_test() (line 145 of /home/admin/domains/peace-in-the-city.be/public_html/sites/all/modules/ctools/includes/object-cache.inc).


Additional

PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: INSERT INTO {watchdog} (uid, type, message, variables, severity, link, location, referer, hostname, timestamp) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9); Array ( [:db_insert_placeholder_0] =&amp;gt; 1 [:db_insert_placeholder_1] =&amp;gt; php [:db_insert_placeholder_2] =&amp;gt; %type: !message in %function (line %line of %file). [:db_insert_placeholder_3] =&amp;gt; a:6:{s:5:&amp;quot;%type&amp;quot;;s:12:&amp;quot;PDOException&amp;quot;;s:8:&amp;quot;!message&amp;quot;;s:382:&amp;quot;SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT s.uid, c.updated FROM {ctools_object_cache} c INNER JOIN {sessions} s ON c.sid = s.sid WHERE s.sid &amp;amp;lt;&amp;amp;gt; :session_id AND c.obj = :obj AND c.name = :name ORDER BY c.updated ASC; Array ( [:session_id] =&amp;amp;gt; HWv-9jPhNMHqjMdxRprJh-YmmBQc2y0jWXrbR_68TeA [:obj] =&amp;amp;gt; view [:name] =&amp;amp;gt; article_4pc ) &amp;quot;;s:9:&amp;quot;%function&amp;quot;;s:26:&amp;quot;ctools_object_cache_test()&amp;quot;;s:5:&amp;quot;%file&amp;quot;;s:103:&amp;quot;/home/admin/domains/peace-in-the-city.be/public_html/sites/all/modules/ctools/includes/object-cache.inc&amp;quot;;s:5:&amp;quot;%line&amp;quot;;i:145;s:14:&amp;quot;severity_level&amp;quot;;i:3;} [:db_insert_placeholder_4] =&amp;gt; 3 [:db_insert_placeholder_5] =&amp;gt; [:db_insert_placeholder_6] =&amp;gt; http://peace-in-the-city.be/admin [:db_insert_placeholder_7] =&amp;gt; [:db_insert_placeholder_8] =&amp;gt; 178.118.99.54 [:db_insert_placeholder_9] =&amp;gt; 1426611072 ) in dblog_watchdog() (line 160 of /home/admin/domains/peace-in-the-city.be/public_html/modules/dblog/dblog.module).


Uncaught exception thrown in session handler.

PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT 1 AS expression FROM {sessions} sessions WHERE ( (sid = :db_condition_placeholder_0) AND (ssid = :db_condition_placeholder_1) ); Array ( [:db_condition_placeholder_0] =&amp;gt; HWv-9jPhNMHqjMdxRprJh-YmmBQc2y0jWXrbR_68TeA [:db_condition_placeholder_1] =&amp;gt; ) in _drupal_session_write() (line 209 of /home/admin/domains/peace-in-the-city.be/public_html/includes/session.inc).




I was able to login as another users without any problems. I flush caches and run cron and this have not solve my issue.

How can I troubleshoot this problem ?

You can find the website here.
To troubleshoot, add these lines to your settings.php:

error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);


Once you add these, you should see some error output.