Sometimes if you do not properly delete objects in a Grails/GORM/Hibernate transaction the following error might occur:
deleted object would be re-saved by cascade (remove deleted object from associations)
This message is presented by the org.hibernate.ObjectDeletedException
After some hours of investigation I found a solution to find the cause!
Just place a breakpoint in Hibernates `SessionImpl.java` before the exception is thrown.
There you might lookup the connected objekt in the parentsByChild HashMap of the persistenceContext.
( Source: stackoverflow.com )