In Firefox and Chrome you can't download a powerpoint file containing special characters in the filename using the view file macro. In my example I attached the file "umlaute_öäüÖÜÄß.pptx" to the page and added this macro:

{viewppt:name=umlaute_öäüÖÜÄß.pptx}

. Clicking on the download-link inside the macro works in Internet Explorer 8 and points to this url: https://some.host/download/attachments/12345/umlaute_%C3%B6%C3%A4%C3%BC%C3%96%C3%9C%C3%84%C3%9F.pptx. In FireFox and Chrome however, the link points to https://some.host/download/attachments/12345/umlaute_%F6%E4%FC%D6%DC%C4%DF.pptx and I get a page not found error. So IE uses url-encoding with UTF-8 (which does work) and FireFox & Chrome are using url-encoding with ISO 8859-1, which does not. As a workaround you can download the files directly from the viewpageattachments-page, the download there works fine, even in FireFox & Chrome.

Edit: This is still occurring with later versions of Firefox (up to 29), but no longer in Chrome (at least in version 36).

Workarounds are:

• Rename the file
• Download files from the View Page Attachments page directly