Hi Jose,
Not sure how you proceed to upgrade your Questionnaire plugin. But from the mod/questionnaire/db/upgrade.php we can see that the "summary" field was renamed to "intro" about 4 years ago:
if ($oldversion < 2008070705) {
/// Rename summary field to 'intro' to adhere to new Moodle standard.
$table = new xmldb_table('questionnaire');
$field = new xmldb_field('summary');
$field->set_attributes(XMLDB_TYPE_TEXT, 'small', null, XMLDB_NOTNULL, null, null, null, null, 'name');
$dbman->rename_field($table, $field, 'intro');
/// Add 'introformat' to adhere to new Moodle standard.
$field = new xmldb_field('introformat', XMLDB_TYPE_INTEGER, '4', XMLDB_UNSIGNED, XMLDB_NOTNULL, null, '0', 'intro');
$dbman->add_field($table, $field);
/// Set all existing records to HTML format.
$DB->set_field('questionnaire', 'introformat', 1);
}