It is installed on an Internet server. It’s a dedicated server hosted with Rackspace. The plugin has been working for over a year now so I’m not sure what may have changed recently. I have tried a lot of different troubleshooting methods and no luck. I also just tried to find that setting you mentioned but I don’t see a settings page anywhere.
Complete this form if it is possible for us to take a look at the installation.
If not possible, try creating a PDF with only one field and a new Formidable Form with one field, then map and test. Let us know if the result is the same of a different message.