Fiddler does not work in my network?

You are trying to troubleshoot and issue and as soon as you enable HTTPs decryption in Fiddler the issue you are troubleshooting with Outlook/Skype/Lync/Teams changes or perhaps authentication no longer works. You might see a 'You need a network connection for this' message on the forms authentication window where you are used to seeing your Federation logon prompt.

If you run into those issues you are then either troubleshooting the troubleshooting, or wind up troubleshooting an entirely unrelated issue with takes more time.

If this sounds like you and you are using Fiddler to decrypt traffic then try these steps:

1. In Fiddler click Tools, Options, go to the HTTPs tab, and enter your federation service name into the box for 'skip decryption for the following hosts'. For example that might be sts.contoso.com.

2. If that does not work then Enable AppContainer loopback. To do this click the WinConfig button in Fiddler, click Except All, and save the changes.

You may need to restart Fiddler in order for those changes to take effect. Hopefully that helps!