Andreas Lanz ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *commented* on HHH-16545 ( https://hibernate.atlassian.net/browse/HHH-16545?atlOrigin=eyJpIjoiNmRiZj... ) Re: PersistenceUtilHelper.MetadataCache is not Thread-Safe ( https://hibernate.atlassian.net/browse/HHH-16545?atlOrigin=eyJpIjoiNmRiZj... ) Hi Sanne, thank for the very fast response and fix. The changes you made look good to me and should solve the issue IMHO. Really testing is non trivial - the issue only happens every other week on one of our many test deployment system. Unfortunately we’re still on hibernate 5.6 (update is planned, but will still take some time due to other dependencies). Would it be possible to backport the fix to hibernate 5.6. On a first look it seems easy enough as the changes are very limited and there should not be any conflict. ( https://hibernate.atlassian.net/browse/HHH-16545#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16545#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#100225- sha1:7f918b6 )