The documentation stated that pdf.export is disabled by default, but it apparently isn't. I also tried setting pdf.export=false in my displaytag.properties file without success.
I don't need pdf.export and I don't use it anywhere but I keep on getting the following warning:
Unable to instantiate class for pdf export. org.displaytag.export.PdfView was found, but required libraries are missing: com/lowagie/text/Element
Google told me other people used to experience the same behaviour.