The fuck? I'm trying to automate login for an asp.net website from a C# console app using HttpWebRequests. I used Fiddler to see how the login happens and how the browser obtains the session and auth cookies from the server. When I replicate the same procedure from C#, I am able to get both cookies withoth a problem, but when I try to use them to get data about the user, I get a 500 ISE. What the actual fuck? I've double-checked every single header and the URLs and it's doing literally the same thing as chrome: Get asp session id (POST)-> get an auth cookie (POST username and passwd) -> interact with the site using the session id and auth cookie (GET). And obiviously I don't have access to the server logs... :/