Question about primary key with identity

Hibernate ORM
1

I encountered an error :
NHibernate.AssertionFailure - An AssertionFailure occurred - this may indicate a bug in NHibernate or in your custom types.
NHibernate.AssertionFailure: null identifier

After a long search i came to the conclusion that this happens because my property is defined like this:
PrimaryKey(PrimaryKeyType.Assigned, “TRANSNUM”)
But the database column defined like this: (without identity)
[TRANSNUM] [int] NOT NULL,

Can this issue be the reason for this error?
Also this error occurs at the second request the server is getting forward, the first request is without errors

2

This is the forum for Hibernate ORM in the Java world. If you have questions about NHibernate you must ask in their communities as that is a different project: https://groups.google.com/g/nhusers?pli=1