A new entity was found through the relationship 'Entity\ApplicationVadiIstanbul2018#user' that was not configured to cascade persist operations for entity: Entity\User@000000004d59c9f900007fef1611d03f. To solve this issue: Either explicitly call EntityManager#persist() on this unknown entity or configure cascade persist this association in the mapping for example @ManyToOne(..,cascade={"persist"}). If you cannot find out which entity causes the problem implement 'Entity\User#__toString()' to get a clue.