Hi Kees, in general the development for Zope 2 (latest version) and Zope 4 / 5 is not that much different. You have to read through the update notes. e.g. Chameleon is the new default template engine, some globals are no longer available, moved imports and so on. As you correctly noted, the documentation is not completely up to date. There is just a lack of man power. I suggest you try to follow the migration documentation ( https://zope.readthedocs.io/en/latest/migrations/zope4/index.html ). If you encounter any problems, and you are able to solve them - report them back or update the documentation.... If you cannot solve the problems yourself, don't hesitate to ask. I recommend the https://community.plone.org/ forum - but try to ask some specialized questions - there is no "Zope 5 developer documentation" out there and just hidden from you. You can also have a look at migrated products / packages. If your application is a commercial one, you could hire someone to do the migration for you. If the Python 3 thing is your problem, there is plenty of documentation out there, also from the Plone community: https://docs.plone.org/manage/upgrading/version_specific_migration/upgrade_t... By the way - these mailing lists are usually not used for those kind of questions, but almost only for announcements of new releases. Best, Jürgen ________________________________ Von: Zope <zope-bounces@zope.org> im Auftrag von Kees de Brabander <cj.de.brabander@hccnet.nl> Gesendet: Dienstag, 21. April 2020 12:22 An: zope-announce@zope.org <zope-announce@zope.org>; zope-dev <zope-dev@zope.org>; zope@zope.org Users <zope@zope.org> Betreff: [Zope] Developing 'products' for zope 4 and 5 Hi, I am trying to catch up with the innovation that zope has undergone (I still have an instance running under zope 2.10.9). Is there any more extensive documentation on how to develop ‘products’ for zope 4 and 5. In the Zope Developer’s Guide the chapter on Zope products simply starts with the remark that the document is currently being reviewed. best, cb _______________________________________________ Zope maillist - Zope@zope.org https://mail.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - https://mail.zope.org/mailman/listinfo/zope-announce https://mail.zope.org/mailman/listinfo/zope-dev )