I believe that the issue is that FacesUrlTransformer is looking for cid= and thus primefaces' pfdlgcid is also matched. So the FacesUrlTransformer should probably look for ?cid= and &cid= instead. The truth is that those delimiters are probably not standardized, i.e. a web server may allow different query string param delimiters, but it should work in most cases.