When create skeleton is false (the default) and there is no translation for a document, the server will return 404. Zanata client not has a status code client side filter which throws exception on any status over 400. We have places where we want to ignore 404 will try to catch NotFoundException. But resteasy's ClientInvocation.java will wrap anything from ResponseStatusFilter into a ResponseProcessingException and therefore skip our catch block.
To reproduce, choose a project/version with some language untranslated (has to be not touched at all. Can't just revert translation to untranslated state). Then do a pull.