Pending Review
Last Updated: 16 Dec 2019 19:51 by Eric
Created on: 10 Dec 2019 10:17
Type: Bug Report
"Filter Now" dysfunction ,(Some blocking rules are not shown,Some blocking rules don't work)




(Some blocking rules are not shown)


When I use the "filter now" function, it does not filter properly.

It goes like this:

Prior to this, I used the "Filters" feature, but there was always a link that was not blocked.(this url:  )

With the "Filters" function turned on, I used the "Filter now" function several times to block this link, but the result was only blocked at that time, and then came out again.

Now I turn off the "Filters" function, and then use "Filter now" to block that link. As a result, the blocking rule is not displayed in the lower left corner. Other blocking rules can be displayed normally.



Posted on: 16 Dec 2019 19:51

The specific problem here is that Fiddler isn't removing the watson.telemetry sessions because they are setting the HTTP Protocol Violation flag, and sessions with this flag set are not hidden unless the oSession["ui-hide"] flag contains the word Stealth within it. See the May 15th response here:

The specific protocol violation here is that the Watson client is promising a request body but failing to send one.

The simplest way to avoid this problem (if it's traffic you don't care about) is to add the hostname inside the Tools > Options > Skip decryption for box. This will prevent Fiddler from decrypting the CONNECT tunnels to that server, which means it won't see the HTTP Errors and thus won't complain about them.

Eric R | Senior Technical Support Engineer
Posted on: 12 Dec 2019 21:01

Hi Little Bug,

I understand that there is some confusion with Filters in Fiddler. I recommend using Help -> Troubleshoot... feature to enable Filter troubleshooting. This will list the sessions in the Sessions Pane with a strike-through to indicate it is filtered. Note that Sessions that are hidden using Filters are still processed through Fiddler. In this case Filtering doesn't block the Session. It only hides it and then removes it from memory upon completion. Let me try to provide an overview with additional references below. 

There are many ways to apply Filters in Fiddler. The Filter Now function, will apply a specific action against a selected Session. The Filter Tab provides a more robust use of Filtering and Fiddler Script can Filter more precisely and more powerfully. 

The Filter Tab reference documentation provides a more thorough explanation of the features and what they can do. Additionally, the Specific Traffic is Missing documentation explains how to check for each Filter.

I hope this helps. Please let me know if you have any suggestions for making Filtering better in Fiddler as we always welcome your feedback. Thank you for using the Fiddler Feedback Portal.


Eric R | Technical Support Engineer
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Posted on: 11 Dec 2019 06:00

They're separate functions that operate independently of each other, I believe. The "Filter Now" context menu item and the window pane it adds its filters to is its own self-contained filtering module, separate from the "Filters" tab which is a subset of filtering.

Not the most clear, I know.