SQL error when using wikiplugin_contributionsdashboard

Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'tiki-test-20-0.tiki_actionlog.lastModif' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

The query was:

SELECT COUNT(actionId) AS count, DATE_FORMAT(FROM_UNIXTIME(lastModif), '%m/%d/%Y') as date FROM tiki_actionlog WHERE objectType = ? AND lastModif > ? AND lastModif < ? GROUP BY DATE_FORMAT(FROM_UNIXTIME(lastModif), '%Y%m%d') ORDER BY lastModif DESC

* /vagrant/test/tiki-20.0/tiki-index.php : 0 -> {main}(array ( ))
* /vagrant/test/tiki-20.0/tiki-index.php : 681 -> __toString(array ( ))
* /vagrant/test/tiki-20.0/lib/core/Tiki/Render/Lazy.php : 22 -> {closure:/vagrant/test/tiki-20.0/lib/wiki/renderlib.php:347-357}(array ( ))
* /vagrant/test/tiki-20.0/lib/wiki/renderlib.php : 350 -> get_parse(array ( 'page' => '???', 'canBeRefreshed' => '???', 'suppress_icons' => '???', ))
* /vagrant/test/tiki-20.0/lib/wiki/wikilib.php : 802 -> __construct(array ( 'info' => '???', 'originalValue' => '???', 'options' => '???', 2 => '???', ))
* /vagrant/test/tiki-20.0/lib/wiki/wikilib.php : 2118 -> parse_data(array ( 'data' => '???', 'option' => '???', ))
* /vagrant/test/tiki-20.0/lib/parser/parserlib.php : 1369 -> parse(array ( 'options' => '???', ))
* /vagrant/test/tiki-20.0/lib/core/WikiParser/Parsable.php : 252 -> parse_first(array ( 'data' => '???', 'preparsed' => '???', 'noparsed' => '???', 'real_start_diff' => '???', ))
* /vagrant/test/tiki-20.0/lib/core/WikiParser/Parsable.php : 103 -> plugin_execute(array ( 'name' => '???', 'data' => '???', 'args' => '???', 'offset' => '???', 'validationPerformed' => '???', 'option' => '???', ))
* /vagrant/test/tiki-20.0/lib/core/WikiParser/Parsable.php : 472 -> wikiplugin_contributionsdashboard(array ( 'data' => '???', 'params' => '???', 1 => '???', 2 => '???', ))
* /vagrant/test/tiki-20.0/lib/wiki-plugins/wikiplugin_contributionsdashboard.php : 125 -> countByDateFilterId(array ( 'ids' => '???', ))
* /vagrant/test/tiki-20.0/lib/logs/logsquerylib.php : 206 -> countByDate(array ( ))
* /vagrant/test/tiki-20.0/lib/logs/logsquerylib.php : 181 -> fetchAll(array ( ))
* /vagrant/test/tiki-20.0/lib/logs/logsquerylib.php : 325 -> fetchAll(array ( 'query' => '???', 'values' => '???', 'numrows' => '???', 'offset' => '???', 'reporterrors' => '???', ))
* /vagrant/test/tiki-20.0/lib/core/TikiDb/Bridge.php : 32 -> fetchAll(array ( 'query' => '???', 'values' => '???', 'numrows' => '???', 'offset' => '???', 'reporterrors' => '???', ))
* /vagrant/test/tiki-20.0/lib/core/TikiDb/Pdo.php : 135 -> handleQueryError(array ( 'query' => '???', 'values' => '???', 'result' => '???', 'mode' => '???', ))
* /vagrant/test/tiki-20.0/lib/core/TikiDb.php : 174 -> handle(array ( 'db' => '???', 'query' => '???', 'values' => '???', 'result' => '???', ))