I have a single ADFS server that is part of an Active Directory domain. I'm having an issue with a Federated application and have turned to Fiddler to troubleshoot (as I have done in the past) and all of a sudden I'm seeing a strange issue that wasn't happening before.
I'm using fiddler on an administration desktop, so I log on with an admin account, this means when I try to use SSO for a federated app, when I hit ADFS it prompt for authentication. Normally, great no problem, I put in my normal username / password (not the admin account I'm logged on with) it authenticates and off I go to the federated app. This has been working fine for sometime but then recently its started to fail. It never accepts my username / password, just keeps 401, 401, 401, prompting me for username / password again and again.
I know my username / password are fine as I use them every day to log onto my desktop AND it only fails when I have fiddler open. If I close fiddler, I get prompted, enter my creds and it works fine.
It also doesn't matter what browser I use.
Does anyone know what this is? Or know how I can troubleshoot it / gather more info?