The problem is that in version 5.4.3.Final in the Cascade class https://github.com/hibernate/hibernate-orm/blob/c35bce15f90bf3ad4486b22fa2bcb27df05a9452/hibernate-core/src/main/java/org/hibernate/engine/internal/Cascade.java#L217 cascadeAssociationNow}}returns true and executes {{cascadeAssociation( , while in 5.3 it returns false.

I guess the root cause is in the https://github.com/hibernate/hibernate-orm/blob/c35bce15f90bf3ad4486b22fa2bcb27df05a9452/hibernate-core/src/main/java/org/hibernate/cfg/OneToOneSecondPass.java#L96 because in the sample mappedBy}}is empty and the method assignes {{FROM_PARENT}}while the older version has different logic https://github.com/hibernate/hibernate-orm/blob/98ee32415dd72cd1d0096221f0dfb2fba6419bfa/hibernate-core/src/main/java/org/hibernate/cfg/OneToOneSecondPass.java#L97 and assignes {{TO_PARENT

Actually, I haven’t found the doc about the code in the sampe. Doc Hibernate 5.4 while this answer from stfo is ok with the sample’s code stfo answer