In my ongoing saga of switching to
application/xhtml+xml MIME type, I've found another victim: Newsgator (site defunct).
The multitudes of folks checking my site via Newsgator (...whomever that person is; there are a total of two Newsgator subscribers to Iamacamera, and I'm the other...) haven't recieved a site update since I published my Now Serving application/xhtml+xml article.
Error 500, of course, is a generic server error, and there are sub-codes that can assist me in determining the problem. Based on a Microsoft Knowledgebase entry, I adjusted my log file to include HTTP error subcodes. Lo and behold, W3C and Newgator are generating error 500 with sub-code 0.
Zero, of course, is the generic sub-code error-code, so that eliminates certain possibilities but doesn't point definitively to anything in particular.
On my site, the W3C validator gets
application/xhtml+xml, but NewsGator gets
Since you use named entities on your pages, I am not at all surprised that various XML user-agents choke and spit when they receive your pages as
I am 99% confident that I have expunged all instances of unsafe named entities from my pages, but I still only send
application/xhtml+xmlto those UAs that I know support XHTML+MathML.
Call me a worry-wort.