Fiddler: a free web debugging tool

Reset Fiddler’s HTTPS certificates

perform the following steps to recreate the Fiddler root certificate:

1. Click Tools > Fiddler Options.
2. Click the HTTPS tab.
3. Ensure that the text says Certificates generated by CertEnroll engine.
4. Click Actions > Reset Certificates. This may take a minute.
5. Accept all prompts

If you encounter any problems, clear out any old certificates from Fiddler using the following procedure:

1. Uncheck the Decrypt HTTPS traffic checkbox
2. Click the Remove Interception Certificates checkbox
3. Accept any prompts to delete certificates from Windows’ certificate stores
4. Recheck the Decrypt HTTPS traffic checkbox
5. Accept any prompts to add certificates to Windows’ certificate stores