Does any one have a workaround for foreign key not-found issue? The broken foreign key always breaks my object tree retireval. I know I can fix the database, but I don't want that my program come to halt whenever some one did some thing wrong to break the data integrity. I just want to be able to handle this kind exception in the code.

Thanks.

IMHO the best way to prevent this error is to force the data integrity at the database level (using foreign key constraints) - every modern db engine allows to do this. After I've implemented such a policy in my company ( always to use the fk constraints) , I've never seen this error again.

I'd agree, just because you are using NHibernate for persistence, it doesn't mean you can ignore basic database design principles like not allowing "broken" data in there in the first place.

Are there some other applications accessing your database; otherwise you might be missing a "cascade" attribute in some of your mapping files to force the children to be deleted if the parent is deleted.