[mikeash]

Additionally, there's nothing inherent about open source that avoids this sort of problem. An open source project could decide on exactly the same sort of upgrade path, where they support current-minus-one versions and that's it.

In theory, open source is better because the old code is still out there and you can get it up and running to upgrade your data. In practice, it can be pretty tough to get open source code that hasn't been maintained in years to build and run properly on a current OS install.

[yuhong]

I think LibreOffice 4.0 abandoned support for the old StarOffice binary format for example.

[ccozan]

Yes, but you can download and install at minimal cost any old version of Libre/Openoffice and read your Staroffice documents. You are not quite left stranded. And also I assume the code to read that format still resides in a repository, cann be pulled and reused at will. Not the same happens with proprietary software.

[davidgerard]

And even Apache OpenOffice abandoned them. Basically the old binfilter was that horrible.

[laurent123456]

It's relatively easy to install an old version of XP or Debian on VirtualBox to run the old software though, and that would be enough to export the documents to a newer format. In comparison, OSX is generally hard to get running on VirtualBox.