I have a new installed CiviCRM 5.1.1 property on my server.
My current system configuration is:
The problem: I importet a few contacts but I realized that besides using the search function in the upper left corner and using custom reports I receive an error 500 and no results.
For example, when I use contacts > find contacts I receive an Error 500 for the following URL: http://mydomain.de/wp-admin/admin.php?page=CiviCRM&q=civicrm/contact/search in Wordpress Debug Mode:
Fatal error: Uncaught Error: Call to undefined method CRM_Core_DAO::disableFullGroupByMode() in /var/www/vhosts/xxx.mydomain.de/wp-content/plugins/civicrm/civicrm/CRM/Contact/BAO/Query.php:4848 Stack trace: #0 /var/www/vhosts/xxx.mydomain.de/wp-content/plugins/civicrm/civicrm/CRM/Contact/Selector.php(1181): CRM_Contact_BAO_Query->searchQuery(NULL, NULL, NULL, false, false, true) #1 /var/www/vhosts/xxx.mydomain.de/wp-content/plugins/civicrm/civicrm/CRM/Utils/PagerAToZ.php(108): CRM_Contact_Selector->alphabetQuery() #2 /var/www/vhosts/xxx.mydomain.de/wp-content/plugins/civicrm/civicrm/CRM/Utils/PagerAToZ.php(136): CRM_Utils_PagerAToZ::getDynamicCharacters(Object(CRM_Contact_Selector), false) #3 /var/www/vhosts/xxx.mydomain.de/wp-content/plugins/civicrm/civicrm/CRM/Utils/PagerAToZ.php(52): CRM_Utils_PagerAToZ::createLinks(Object(CRM_Contact_Selector), NULL, false) #4 /var/www/vhosts/xxx.mydomain.de in /var/www/vhosts/xxx.mydomain.de/wp-content/plugins/civicrm/civicrm/CRM/Contact/BAO/Query.php on line 4848
Could anybody please help with this issue? I was trying to fix it for some time now and searched the whole forum with no result or hint. Thanks a lot in advance.