I found out that there is nothing wrong with the code in the end, by just removing the UUID id from the User entity Constructor solved the issue, for some reason hibernate tries to create and re-create/overwrite it when the createUser method is invoked requesting a UUID.randomUUID, just by removing it and letting it create by itself just works out, weird though, I had a very similar Api where in the method createUser I had the same structure and worked out normally, don't know, it's running.