A new entity was found through the relationship 'Ibexa\Taxonomy\Persistence\Entity\TaxonomyEntryAssignment#entry' that was not configured to cascade persist operations for entity: Ibexa\Taxonomy\Persistence\Entity\TaxonomyEntry@4475. 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 'Ibexa\Taxonomy\Persistence\Entity\TaxonomyEntry#__toString()' to get a clue.