XFA forms are features of a pdf file involving options to complete fields in certain documents - in many cases official documents. These options may open a calendar, for example, in order to select day, month and year, etc. Usually these forms ensure that a certain official format is used.
I have seen that Okular displays a warning that XFA forms are not supported:
More here.
Selecting 'Show forms' in Okular those fields can be edited and changes can be saved, but comparing to what I see in Windows with Adobe Reader only some part of those are really accessed in this way: the calendar options are absent, and the separate fields of day/month/year are not present, which may raise questions on the correctness of the result.
Adobe Reader 9 can still be installed in Ubuntu 14.04 but this seems like a very limited option.
Is there a a native pdf reader that can use fully XFA forms?
(If not, is Wine a solution?)
The solution for Ubuntu 14.04 works in 16.04. too.
The file I tested was here (official French government website).