Migrate from OC7 on windows to OC9 on linux

I am currently running OC on a windows Server 2012R2 but never version don't support windows server anymore.
As I still want to use the latest version and need to keep that server on windows for other reasons I thought about setting up a VM that runs linux to get a newer version of OC.
I have lots of files, calendar and some contact data in my current instance, as well as user settings and so on that I really can't loose. Is there a (preferable easy) way to migrate that data? Has anyone perhaps done that before and can give me some tips? Thanks!


there is no official upgrade path. The cleanest way is to backup your files, contacts and calendars on client-side. setup a fresh installation of 9.1.2 and re-import that data from the client back.

The main problem are the filenames, not sure if you can migrate from OC 7 on Win to OC 7 on Linux, re-run the filecache-index. It could work but you risk to carry a lot of old stuff in your setup that could cause problems at a later point. Then from OC 7 you would have to upgrade all major versions in between (8.0, 8.1, 8.2, 9.0, 9.1). Even if it takes you an afternoon to make the new setup, it will probably less work than doing all this migration where you can't be sure that it works properly. If it is a very large setup, you could consider taking an enterprise subscription and ask for assistance (originally, it was promised to provide migration scripts for old Win-setups).

edit: for shared objects, this won't work properly: https://github.com/owncloud/core/issues/21063