I need to use an old version (4.2)

It is possible to buy an old version (4.2) of Storyboard Pro?
or export from 5.5 to 4.2?

Storyboard Pro is backward compatible. Any projects saved in the previous version of Storyboard Pro will be opened fine in 5.5. But once it is saved in 5.5, it can not be working anymore in previous version of Storyboard Pro

As for buying an older version of Storyboard Pro, please contact sales@toonboom.com for more details.

Based on your answer, I believe this should read “Storyboard Pro is Not backward compatible”

To be “backwards compatible” the software just has to be able to read and open files created with older versions of the same software. *

https://www.google.com/search?q=what+does+backwards+compatible+mean&ie=utf-8&oe=utf-8

It does not mean you have the option to save a current project in a legacy format. That is known as “file versioning.”

File versioning is not supported in Toon Boom products.

https://www.google.com/search?q=file+versioninng&ie=utf-8&oe=utf-8#q=file+versioning

  • Note: Although the files can be read and opened, certain processes may have changed significantly and may require a degree of conversion, deformation in Harmony is converted using a script for instance.