Specific websites refuse to connect to Fiddler on Windows 10

[SHOW]

I am using Windows 10 (it may work fine on Windows 11).

I was unable to capture the link below using Fiddler Classic and Fiddler Everywhere (trial version).

I think Fiddler Everywhere does not support TLS 1.3 successfully in Windows 10. If there is a way to force the connection to TLS 1.3 in Fiddler Everywhere, it may work, but I could not find such a setting.

I have confirmed that 3rd party network capturing tools successfully capture the link below, but why only Fiddler Classic and Everywhere fail? If Windows 10 does not fully support TLS 1.3, then 3rd party capturing tools should not work either, but since 3rd party programs work perfectly, I am wondering why this symptom only occurs in Fiddler.

1. Turn on Fiddler Classic or Everywhere and capture the link below, and it will be rejected.
2. Turn off Fiddler and access the link below, and it will work normally.

https://smartstore.naver.com/powermtb/products/6236194845

[Nick Iliev]

Hello,

 

Fiddler Everywhere supports TLS 1.3 and HTTP/2, while Fiddler Classic only supports HTTP 1.x and TLS 1.2. However, it's important to note that, according to Microsoft’s official documentation, Windows 10 does not have TLS 1.3 enabled by default.

 Note

TLS 1.3 is supported starting in Windows 11 and Windows Server 2022. Enabling TLS 1.3 on earlier versions of Windows is not a safe system configuration.

The same documentation section provides a detailed comparison table showing that support for TLS 1.3 is not enabled on any version of Windows 10.

 

Additionally, it seems the specific server has additional anti-bot measures, which can reject some repetitive requests. 

 

In our tests on Windows 11, where TLS 1.3 is supported by default, we successfully captured the initial page load by enabling HTTP/2 support and selecting the "Ignore server certificate errors" option in Fiddler Everywhere.

 

Enabling "Ignore server certificate errors" option

 

Enabling HTTP/2 support

Using the Browser capturing mode to capture traffic from https://smartstore.naver.com/powermtb/products/6236194845 

Regards,
Nick Iliev
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