Fiddler fails after CONNECT to HTTPS service

14
votes

Fiddler is unable to connect to my https server and is failing in the CONNECT stage itself. Firefox opens the site just fine. Here [1] is a screenshot of the requests. I tried with Charles and it was able to list the request but failed to decrypt the requests [2].

Please note that other HTTPS services seem to be working fine with fiddler

1: http://imgur.com/Zzu8lKS

2: http://imgur.com/dAbz6AK

4
fiddler
More details are needed. Did you trust the Fiddler HTTPS certificate? What is the client application? What do you see on the Log tab? - EricLaw
Yes, the certificates were installed. Also, traffic from other applications are showing up in Fiddler. This is one of our internal applications developed in QT. - Abhi
I am using the latest fiddler(v4.4.3.0 beta). Here's the log dump from the requests. pastebin.com/7bL3zmfH - Abhi
The error message is coming from your application, which is returning a TLS Fatal Alert upon receiving Fiddler's interception certificate. Either QT has its own certificate store, or it doesn't like makecert-generated certificates for some reason. Try 1. Disable HTTPS decryption in Fiddler and click Remove Certificates. 2. Install fiddler2.com/dl/FiddlerCertMaker.exe 3. Restart Fiddler. 4. Reenable HTTPS decryption. Do you get the same error message in the LOG tab? - EricLaw
I did as you said. The same error messages appear: 10:09:35:4534 !SecureClientPipeDirect failed: A call to SSPI failed, see inner exception. < An unknown error occurred while processing the certificate on pipe 16 - Abhi

4 Answers

21
votes

Tools/Options/HTTPS ... Change TLS1.0 to TLS1.2 worked for me ...

enter image description here

4
votes

I did add Fiddler root certificate in IE and Firefox. Still I was getting this ..... System.Security.Authentication.AuthenticationException A call to SSPI failed The function requested is not supported fiddler

I solved this by adding tls1.2 & tls1.2 under Tools--> Fiddler Options --> HTTPS (Tab) --> Enabled Protocols, and Fiddler started capturing https traffic from browsers.

2
votes

I had a similar issue with all SSL sites. It seems to happen when there are a lot of certs in the following folder C:\Users\<username>\AppData\Roaming\Microsoft\SystemCertificates\My\Certificates

stopping fiddler, emptying the folder and starting it up again fixed the issue for me.

0
votes

What worked for me:

Tools -> Fiddler Options -> HTTPS -> Reset All Certificates

Then I got prompted to create a new Fiddler certificate and trust it via windows.