How To Use Fiddler To Debug An Issue?

How to use Fiddler to debug an issue?

Issue Description: How to use Fiddler to debug an issue?

Background: Fiddler is a proxy service that can be very useful for debugging issues. Most HTTP clients will not automatically log HTTP debugging information. For example, the .Net HTTP client requires a special debug build to do this. As such most HTTP client debugging is done with tools like fiddler. Its is a very common tool used across the industry (as of writing this).

A good article about proxies can be found in the Knowledge Article: Robot & Proxy Working Details . This article covers proxies as it relates to the Robot. But the section Proxy Fallback applies to applications in general.

Typically when using fiddler, it requires either the application to be configured specifically for the proxy or just configurating the user profile of the user running the application to use the Proxy. Fiddler will take care of the User proxy settings automatically.


  1. This method of debugging relies on fiddler configuring the user profile proxy and that proxy configuration being applied to the application being debugged.
  2. This means that the application must be running as the user who is also running fiddler.
  3. Here are some examples:
    1. There is an issue that requires us to debug the Robot Executor. The user logs into the Robot machine as the Robot user. They start Fiddler and follow the instructions in the this article.
      • This will generate HTTP traffic from the user and also any applications the user is running that makes HTTP requests, including the Robot Executor.
    2. The is an issue with the Robot Service for an unattended bot. The user logs into the Robot machine as the Robot user. They start Fiddler and follow the instructions in the this article.
    3. There is an issue where the user needs to debug HTTP requests made by Orchestrator to the Identity Server. The admin logs into the Orchestrator server and follows this KB article. The admin is logged into an account named admin but Orchestrator is running as the service account uipath_orchestrator.
      1. This will not generate traffic because Orchestrator is not running as admin.
      2. Either, the admin needs to login as the uipath_orchestrator account and start fiddler, or they need to configure an application proxy setting for Orchestrator, refer Orchestrator Installation Considerations - Using Environment Variables for mor einformation.

Using Fiddler
  1. Download and install (as Admin) Fiddler Classic
  2. Open Fiddler
  3. Tools > Options
  4. Set the HTTPS tab to the following configuration. Ensure Decrypt HTTPS traffic is checked. If these steps aren't followed, the trace file will not be useful.
  1. Click Yes:

Fiddler Cert

Security warning


TrustCert Success
  1. Set the Connections Tab to the following configuration

  1. Once it is connected, it should be possible to see traffic. It should look similar to below. If the traffic is grayed out, that means that HTTPS decryption is not working. If this is the case, re-verify steps 4-6 or contact UiPath for help.

  1. Reproduce the issue. Then to save, go to File > Save > All Sessions and save it as .saz .