Using Fiddler for Troubleshooting Windows 10

Fiddler is a free web debugging proxy server tool which logs HTTP(S) traffic to quickly obtain all network communications to and from the device. Instead of requesting and analyzing verbose server logs, you can significantly reduce Windows 10 troubleshooting efforts by using the Fiddler tool.

This exercise helps you to download, install, configure and use this free tool on a Windows 10 device.

Installing Fiddler

Find Fiddler download in Web search

In our already launched Google Chrome browser:

  1. Click the New Tab button.
  2. Enter fiddler in the Search box. 
  3. Select Fiddler - Free Web Debugging Proxy - Telerik.

Note: You can also navigate to https://telerik.com/download/fiddler.

1. Free Download

Click Fiddler free download button

Click Free download.

2. Download for Windows

Fields to complete Fiddler download.
  1. Select Client application development/debugging in the drop-down menu.
  2. Enter your email address, for example, hol@hol.com in Your Email field.
  3. Select the I accept the Fiddler End User License Agreement check box.
  4. Click Download for Windows.

3. Run Fiddler Setup

Click FiddlerSetup.exe to run the Fiddler installer.

4. Accept License Agreement

Fiddler license agreement

Click I Agree.

5. Select Installation Folder

Install Fiddler.

Click Install.

6. Complete Installation

Close fiddler installation box.

Click Close.

Configuring Fiddler

In this section, learn how to configure Fiddler on a Windows 10 device to capture all HTTP(S) traffic to and from the device. This aides Windows 10 troubleshooting, by allowing you to see what Workspace ONE UEM is sending and receiving from the device.

1. Launch Fiddler

Launch Fiddler on a Windows 10 device.
  1. Click the Windows logo to launch the Start Menu.
  2. Search for fiddler.
  3. Click Fiddler 4.

2. Disable Warning

Click Cancel.

3. Select WinConfig

Click WinConfig.

4. Dismiss Orphaned Exemption Record Found

Click No.

5. Configure AppContainer Loopback Exemption Utility

  1. Click Exempt All.
  2. Click Save Changes.
  3. Click the X to close the AppContainer Loopback Exemption Utility pop-up window.

Note: If you do not want to Exempt All, you can accept  Work or school account, or any of the immersive apps you want to capture traffic for. This setting captures UWP application traffic and setting on Windows 10. By default, Fiddler captures traffic only for Win32 app types.

6. Decrypt HTTPS Traffic

  1. Select Tools.
  2. Select Options...

7. Check Decrypt HTTPS Traffic

Select the Decrypt HTTPS traffic check box.

8. Trust Root Certificate

Click Yes.

9. Install Root Certificate

Click Yes.

10. Confirm Root Certificate Install

Click Yes.

11. Trust Root Certificate Added Success

Click OK.

12. Trust Root Certificate

Click X.

Running and Analyzing Fiddler Captures

In this section, use Fiddler for troubleshooting Windows 10 issues. Learn how to run a quick capture, view the data in RAW and XML formats, and save your captures.

1. Start and Stop Captures

Start and stop captures when troubleshooting windows 10.

To toggle Capture Traffic on and off, you can either press F12 or select File > Capture Traffic.

After initial installation, Fiddler starts capturing by default. Note the Capturing message in the bottom left corner.

2. Inspect Traffic

Inspect traffic for Windows 10 troubleshooting.

To toggle Capture Traffic on and off, you can either press F12 or select File > Capture Traffic.

  1. Select the first item in the list, where Host is www.fiddler2.com.
  2. Click Inspectors. 
  3. Select Raw or the most suitable view for your troubleshooting. Because most MDM communication is in SyncML format, for Windows 10, always select XML.
  4. Click Response body is encoded. Click to decode.
  5. Select Raw.

3. Start and Stop Captures

The upper window shows what is sent from the device to the endpoint, and the lower window shows the response from the server to the device. When Fiddler is first launched, it attempts to check for updates and sends its current version. The server then replies with the latest version of Fiddler and the release notes for the latest releases. This is a simple example to show the type of information we can retrieve, but for our troubleshooting we can use this method and tool to debug enrollment issues and pushing profiles, for example.

4. Apply Filters

Apply Fiddler filters for troubleshooting Windows 10.

When troubleshooting Windows 10, you can filter out all the noise other than your device services server, by adding a filter:

  1. Select the Filters tab.
  2. Select the Use Filters check box.
  3. Select Show only the following Hosts.
  4. Enter your host name, for example, hol.awmdm.com.
  5. Select Actions > Run Filterset now.

Note: You can also quickly filter and apply other helpful actions by right-clicking one of the traffic elements in the left pane. You can get advanced and replay requests and even modify data before replaying the request to see if it changes the response.

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