Although URLs have to be url-encoded, this is a concept which is not well understood by non-tech people, who the GWT audience belongs to. As a consequence, If the GWT XML contains a non url-encoded URL, the download seems to fail. I have seen GLAM people believing that GWT was not able to deal with non-ascii characters just because the URLs they had put in the XML were not url-encoded. All this tends to generate "broken" filenames (for example: with French words, but without their accents - which is wrong) and generates in any case additional work on GLAM side. That' s why I propose that GWT detects if URLs are already url-encoded in the XML, and url-encodes them if necessary before starting the download.