On many occasions, I've found Fiddler stops working on SSL connections for no apparent reason. Chrome gives errors like 'untrusted cert authority'. It seems to happen after Windows or browser updates and I've tried every approach I could find to fix it.
I think I've finally found a reliable fix:
1. Open Windows Certificate Manager and manually delete all Fiddler certs from all folders
2. Open Fiddler HTTPS options tab, uncheck 'Capture HTTPS connects'
3. Click 'Remove Interception Certificates' in the Actions menu.
4. Restart Fiddler
5.Recheck 'Capture HTTPS connects' in Fiddler options, and reinstall the certs.
Removing all Fiddler certs in Windows Cert Manager first seems to be the key step.