I tried to fix the Content-Type of a feed in my app, I read the Response Class documentation and it had a line of code (didnt try Expires)):

self.response.headers.add_header('Expires', expires_str)

Needless to say I adopted it and made it to be:

self.response.headers.add_header('Content-Type', 'application/rss+xml; charset=utf-8')

It works on Development Server but not on Production Server, so I also tried after I read wsgiref.headers:

self.response.headers.add_header('content-type', 'application/rss+xml', charset='utf-8')

Still no luck.

I searched on discussion group, then I found everyone coded in this way (and I actually didnt like this way):

self.response.headers['Content-Type'] = 'application/rss+xml; charset=utf-8'

And it works. I have no idea whats going on Production server and I didnt bother to look into it.