I spent some time today searching for a bug. Turned out it was a nasty one.
If you have a single line of code, being there for a single purpose, you usually expect this code to work.
My case: Setting a HTTP header on a response to a normal HTTP request. One probably would think this is a normal task. I wanted to set a header to control caching. More specifically, the ‘vary’ header, as the result of the request is dependent upon a specific header sent with the request.
Continue reading “Why the IIS overwrites your vary-Header with ‘Accept-Encoding’”