For further support, go to www.adobe.com/support/products/acrreader.html’
or
"Please wait...
PDFNet actually renders the page correctly. The file that generated the placeholder page is Adobe LiveCycle. The problem is that the file contains proprietary LiveCycle specific extensions that are processed only in recent versions of Acrobat reader on desktop. These extensions are not supported by third party viewers and are not supported even in mobile versions of Acrobat.
For more info please see:
https://groups.google.com/d/topic/pdfnet-sdk/ghFsTeAxDuI/discussion
https://groups.google.com/d/topic/pdfnet-sdk/MivJgR8Oa8A/discussion
https://groups.google.com/d/topic/pdfnet-sdk/zgoiXfCf_bU/discussion
In case you want to detect this type of files programmatically (e.g. to show your own message instead of the LiveCycle one) use the following code snippet (it's in Java, but you can easily port it to other languages):
PDFDoc doc = new PDFDoc("doc.pdf");
Obj objNeedsRendering = doc.getRoot().findObj("NeedsRendering");
if (objNeedsRendering != null && objNeedsRendering.isBool() && objNeedsRendering.getBool()) {
// The document has XFA forms and is not supported
} else {
// The document is supported
}