Some codes have been created using a pasted URL with urlencoding (e.g. ' was pasted as %27). This has caused problems because the QR Code encodes the url further rendering it as %2527.
I temporarily fixed the problem by removing one urlencoding step in the qrwp.org forwarder code.
However, this needs fixing long term.
I suggest that QRpedia.org interface needs to silently convert any encoded urls into their un-encoded variant. And we need some sanity checking in the forwarder code to handle edge cases.