Hi,
Yes all projects and plugins will be imported seamlessly. Note that you will need to retrain your visual machine learning models, and replay the R integration script if needed. The details of upgrading DSS are highlighted in our release notes, including a few limitations and warnings: https://doc.dataiku.com/dss/latest/release_notes/4.2.html . [EDIT] This assumes that you upgrade DSS on the existing machine, following this documentation: https://doc.dataiku.com/dss/latest/installation/upgrade_instance.html
Cheers,
Alex