Hi all, good news on the backwards compatibility; David suggested we could use his "bridger" tool to have the Session API binary compatible with older versions. - https://github.com/dmlloyd/bridger I created a prototype patch, it's all actually quite self-explanatory: - https://github.com/Sanne/hibernate-orm/commit/8d14a5efa29e6682a7d823a2252... I had more trouble testing it. Here a failed approach: I could not get Gradle to compile with a different version used for testing, while at the same time not driving dependencies in my IDE nuts :) - https://github.com/Sanne/hibernate-orm/commit/28f5110cf9ccee9614bceb45403... Next, I resorted to an external, trivial Maven project; this worked beautifully! You can see the warnings in the logs suggesting "you're using a method which doesn't exist anymore, but it's ok.." . - https://github.com/Sanne/binary-compatibility-test Next steps: # Agree on applying the approach? I see no problems with it but clearly this will need to be supported by us all. # Figure out how to get the integration tests working in the ORM / Gradle build # Fix some pending problem with Envers: it's no longer compiling as a non-abstract extension of Session doesn't implement getFlushMode; might be tricky or not, I've not looked yet. # See if we can avoid listing the placeholder method in javadocs Thanks, Sanne