Phalcon\Di\Exception: Call to undefined method or service 'getschema'

Hi,

we have a CMS based on Phalcon 2.x and we're trying to update it to 3.x Basically it's a bunch of extensions for default phalcon classes. For example our lib\module extends \Phalcon\Mvc\User\Module

The problem: Phalcon\Di\Exception: Call to undefined method or service 'getschema'

xdebug backtrace:
#0  Phalcon\Di->__call(getschema, Array())
#1  Phalcon\Mvc\Model\Query->_prepareSelect()
#2  Phalcon\Mvc\Model\Query->parse()
#3  Phalcon\Mvc\Model\Query->execute()
#4  Phalcon\Mvc\Model::findFirst(Array([conditions] => uri = ?0 AND uriIndex = ?1, [bind] => Array([0] => swm, [1] => 0)))

Any ideas?