XFA (XML Forms Architecture) is a technology that is sometimes used to create PDF forms. However, it is an older technology that is no longer widely supported by modern PDF viewers.

To open the file, you may need to use a PDF viewer that supports XFA forms. One option is to try opening the file in Adobe Acrobat or Adobe Reader, as these programs may have better support for XFA forms. Alternatively, you could try converting the file to a different format, such as a standard PDF form or an HTML form.

There are also online conversion tools available that can convert XFA forms to standard PDF or HTML forms. However, be aware that converting the form may cause some loss of functionality, depending on how complex the form is.

If you're still having trouble opening the file or converting it, you may want to reach out to the organization or individual who provided the file and ask if there is a different format available.