Office 365 extension chrashes Fiddler

[Lennart]

When using O365 extension and trying ws-fed auth to O365 fiddler chrashes, fiddler works alright when disabling extension

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Uncaught Exception in Session #387
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Fiddler has encountered an unexpected problem. If you believe this is a bug in Fiddler, please copy this message by hitting CTRL+C, and submit a bug report at http://www.telerik.com/forums/fiddler.

Length cannot be less than zero.

Parameter name: length

Type: System.ArgumentOutOfRangeException
Source: mscorlib
   at System.String.Substring(Int32 startIndex, Int32 length)

   at EXOFiddlerInspector.SessionProcessor.SetAuthentication(Session session)

   at EXOFiddlerInspector.Services.ActivationService.AutoTamperResponseAfter(Session _session)

   at Fiddler.FiddlerExtensions.(Session ) in C:\Jenkins\Fiddler_Windows\workspace\Fiddler2\Common\Application\Extensions.cs:line 866

   at Fiddler.Session.‘() in C:\Jenkins\Fiddler_Windows\workspace\Fiddler2\Common\Core\Session.cs:line 4073

   at Fiddler.ServerChatter.ŽŒ() in C:\Jenkins\Fiddler_Windows\workspace\Fiddler2\Common\Core\ServerChatter.cs:line 1520

   at Fiddler.ServerChatter.Œ() in C:\Jenkins\Fiddler_Windows\workspace\Fiddler2\Common\Core\ServerChatter.cs:line 1474

   at Fiddler.Session.‘() in C:\Jenkins\Fiddler_Windows\workspace\Fiddler2\Common\Core\Session.cs:line 3751

   at Fiddler.Session.(Object ) in C:\Jenkins\Fiddler_Windows\workspace\Fiddler2\Common\Core\Session.cs:line 3526


Fiddler v5.0.20194.41348 (x64 AMD64) [.NET 4.0.30319.42000 on Microsoft Windows NT 10.0.18363.0]
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OK   
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[Eric R | Senior Technical Support Engineer]

Hi Lennart,

Thank you for the stack trace. It appears the extension is failing in the extension SetAuthentication method. After reviewing the Extension's GitHub Repository I found this closed Issue which may be related. I recommend updating the extension to the latest version.

As you mentioned, since Fiddler works fine without the extension enabled, this is not likely an issue with Fiddler. The good news is that the Office 365 Extension is an open-source project and issues can be logged on their Issues Repository. They may even take pull requests. 

I hope this helps. Please let me know if you need any additional information regarding Fiddler. 

Regards,

Eric R | Senior Technical Support Engineer
Progress Telerik