Stack trace:
#0 D:wampwwwsocialengineapplicationlibrariesZendAuthAdapterDbTable.php(306): Zend_Auth_Adapter_DbTable->_authenticateQuerySelect(Object(Zend_Db_Select))
#1 D:wampwwwsocialengineapplicationlibrariesZendAuth.php(117): Zend_Auth_Adapter_DbTable->authenticate()
#2 D:wampwwwsocialengineapplicationmodulesUserApiCore.php(179): Zend_Auth->authenticate(Object(Zend_Auth_Adapter_DbTable))
#3 D:wampwwwsocialengineapplicationmodulesUsercontrollersAuthController.php(144): User_Api_Core->authenticate(‘m.georgiev@visc…’, ‘socialengine’)
#4 D:wampwwwsocialengineapplicationlibrariesZendControllerAction.php(513): User_AuthController->loginAction()
#5 D:wampwwwsocialengineapplicationlibrariesZendControllerDispatcherStandard.php(289): Zend_Controller_Action->dispatch(‘loginAction’)
#6 D:wampwwwsocialengineapplicationlibrariesZendControllerFront.php(946): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#7 D:wampwwwsocialengineapplicationmodulesCoreBootstrap.php(75): Zend_Controller_Front->dispatch()
#8 D:wampwwwsocialengineapplicationlibrariesEngineApplication.php(99): Core_Bootstrap->run()
#9 D:wampwwwsocialengineapplicationindex.php(187): Engine_Application->run()
#10 D:wampwwwsocialengineindex.php(15): include(‘D:wampwwwsoc…’)
#11 {main}
====================

The reason is:

Error in query: Illegal mix of collations (latin1_general_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation ‘=’

Here is the fix:

use socialengine;

ALTER TABLE engine4_users CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;