This issue was originally reported on the MediaWiki Users forums in this thread:
The original reporter tested this on MW version 1.13.2 and 1.15.1, using PHP version 5.2.9 using IIS7.5 on Microsoft Server 2008. I have duplicated this behavior on a VMWare virtual machine running Windows 7 Ultimate, using IIS 7.5 and PHP version 5.2.12 with MW version 1.15.1 and 1.16alpha.
The test urls used to generate this error are:
The issue in question is the presence of special characters in the title name when a colon is also present and there are special characters preceding the colon.
When MediaWiki encodes the title and sends redirect headers in OutputPage::output(); IIS7.5 is returning a 404.0 error, and IIS7.5 indicates that the requested URL is in the format:
http://localhost:80/w/index.xn--php?title=-14a:%C3%A1 (first url above)
http://localhost:80/w/index.xn--php?title=-14a:Test (second url above)
So, at some point it appears that IIS7.5 is rewriting the URL redirect.
Setting $wgDebugRedirects = true; circumvents this error by generating a link to the redirect page instead.
This may in fact be a IIS7.5 bug, but at this point Microsoft's stand is that this is an application error.
This issue was found and tested against IIS7.5 but may in fact have been introduced in IIS7.
This issue is browser independent; it has been recreated in IE8, IE7 and Firefox 3.6.
OS: Windows 7