We get the follwoing error with an enabled LDAP configuration, when a users logs in the first time:

Fatal error: Cannot redeclare class +ExpressionManager in /var/www/html/limesurvey/application/helpers/expressions/em_core_helper.php on line 30

Debugging showed me, that the file em_core_helper.php is loaded twice. Thus the following line is called twice (approx line 320 in ./framework/YiiBase.php):

require($path.'.php');

Our current workaround is to change this line to

require_once($path.'.php');