The error is: "The class 'Doctrine\ORM\Persisters\ManyToManyPersister' was not found in the chain configured namespaces"
Replicate by making an entity which has a property which is self referencing; e.g. http://docs.doctrine-project.org/en/latest/reference/association-mapping.html#many-to-many-self-referencing .
For example an Album could be related to any other similar albums. An album entity would have a property 'relatedAlbums' which is an ArrayCollection. Similarly, I could be working on a CMS where any piece of content could be related to any other in order to show a "related content" or "related posts" style list on a web page.
Using Symfony 2.1 and a Symfony Form with FormBuilder make sure to use the 'by_reference' => false to call the setter for the property. In the setter for the property: https://gist.github.com/3879169
A similar question has been asked on StackOverflow: http://stackoverflow.com/questions/12077084/doctrine2-manytomany-self-referencing