Hi, When setting up an Android device with Fiddler on the host machine, you need to set up proxy settings on Android Wi-Fi giving the IP address shown on Fiddler (Online) as host and port as 8888. After that, you need to visit http://ipv4.fiddler:8888 on your browser to download the Fiddler Root Certificate. However, when visiting the http://ipv4.fiddler:8888 on the Android browser, you might get ERR_CONNECTION_ TIMED_OUT.  This could be due to many reasons.

Reasons and Solutions:

• If you are connecting your Android with Fiddler for the first time recheck the settings on Fiddler. Goto -> Tools -> Options -> Connection -> Tick “Allow remote computers to connect”.  To allow HTTPS decryption, ensure you have ticked “Decrypt HTTPS traffic” under Options-> HTTPS, and then install the root certificate.
• If you are trying to reconnect you Android with Fiddler which was working with a different host, and now getting  ERR_CONNECTION_ TIMED_OUT on the Android browser,
  • You can first try removing current certificates on the Fiddler host machine and try reinstalling the certificates..
    • First, Goto -> Tools -> Options -> HTTPS-> Untick “Decrypt HTTPS traffic”.
    • Then, select ‘Actions’ on the same dialog -> select “Remove interception certificates”
    • Then follow the normal procedure to enable HTTPS traffic decryption
  • The ultimate try is to uninstall and reinstall the Fiddler from the beginning on your host machine. After that, your Android browser can visit http://ipv4.fiddler:8888 and download a new Fiddler Root Certificate.

Plus:

Even after successfully installing the Fiddler root certificate on your Android device, if you are not able to capture the HTTTPS traffic. It might be that you are using an older fiddler root certificate or a certificate you installed when working with a different Fiddle r host machine. Hence, remove the current installed certificate from your android device. After that, try reconnecting with the Fiddler host to reinstall the new root certificate.

adb shell
cd /data/misc/user/0/cacerts-added
ls
rm < current root certificate e.g. e5c3944b.0>

In the worst case It may be due to certificate pinning used in the application you are trying to test. In that case, you may have to use an instrumentation tool like Xposed to bypass such conditions.

Cheers ! 🙂