Timon Zilles ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *commented* on HHH-16991 ( https://hibernate.atlassian.net/browse/HHH-16991?atlOrigin=eyJpIjoiYTIwMD... ) Re: EnhancedUserType cannot be used when defining relations ( https://hibernate.atlassian.net/browse/HHH-16991?atlOrigin=eyJpIjoiYTIwMD... ) I don’t know what your actual problem is, but when I use your code of MyType , set it to public and change the code of the disassemble method from @Override public Serializable disassemble(MyId value) { return value.text; } to @Override public Serializable disassemble(MyId value) { return value; } it works in my test case. If I don’t do this adjustment I get a CIRCULAR REFERENCE: java.lang.ClassCastException. If there are other problems it would be interesting for me to know about them in order to decide whether we can use this EnhancedUserType. ( https://hibernate.atlassian.net/browse/HHH-16991#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16991#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100233- sha1:62cfdef )