To use Fiddler with Windows 8+ "Metro"/"Immersive" applications, you must do two things:
1> When prompted to trust the Fiddler Root Certificate machine-wide, accept that prompt (Fiddler) or install the certificate in the CurrentMachine store yourself (FiddlerCore).
2> You must exempt the AppContainers from Loopback restrictions; see http://blogs.msdn.com/b/fiddler/archive/2011/12/10/fiddler-windows-8-apps-enable-loopback-network-isolation-exemption.aspx or the WinConfig
button on Fiddler's toolbar.
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