Yoann Rodière ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *commented* on HHH-16199 ( https://hibernate.atlassian.net/browse/HHH-16199?atlOrigin=eyJpIjoiMDQzN2... ) Re: org.hibernate.AssertionFailure: force initializing collection loading ( https://hibernate.atlassian.net/browse/HHH-16199?atlOrigin=eyJpIjoiMDQzN2... ) Interestingly, the reproducer uses org.hibernate.dialect.MySQL8Dialect , which is deprecated and probably shouldn’t be used. Setting the dialect to org.hibernate.dialect.H2Dialect fixes the test, but I suppose that’s beside the point since H2 is started in “MySQL mode”. Setting the dialect to org.hibernate.dialect.MySQLDialect , I get a different exception, probably because we handle IDs differently on newer versions of H2 and/or MySQL. Setting the dialect to org.hibernate.dialect.MySQLDialect and switching to MySQL (instead of H2), I actually get the same exception again. I sent a PR with everything I did to simplify your reproducer: https://github.com/ls-urs-keller/hibernate-force-initalizing-collection-p... ( https://github.com/ls-urs-keller/hibernate-force-initalizing-collection-p... ) ( https://hibernate.atlassian.net/browse/HHH-16199#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16199#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#100216- sha1:3fa9804 )