Fixing Fiddler HTTPS Certificate Errors
How to resolve certificate errors that occur when capturing HTTPS traffic in Fiddler.
This post was machine-translated from Korean by AI. Some expressions may differ from the original.
Read the original (Korean)- Fiddler Classic (Not Everywhere)
When using Fiddler, you often run into trouble due to HTTPS certificates.
These are usually errors such as certificate expiration, overly long validity periods, or untrusted certificates.
In this instance, the standard solutions found on Google (like certenroll engine reset) didn't work. After struggling for a while, I found a solution and am sharing it here.
(Standard Solution, latest Fiddler version)
Tools - Options - HTTPS - Actions - Reset All Certificates
Usually, the solution above should work, but in the case I encountered, clicking "Reset All Certificates" caused Fiddler to freeze.
Inferring the cause after solving it: during the reset process, Fiddler needs to delete the wildcard certificates it generated. It seems that one of these wildcard certificates could not be deleted, causing Fiddler to hit an Exception and freeze.
Anyway, cutting to the chase: to solve this, you need to manually delete all wildcard certificates installed by Fiddler and the Fiddler root certificates (DO_NOT_TRUST_FiddlerRoot).
Run - certmgr.msc
ā Delete all wildcard certificates in [Personal -> Certificates]
ā Delete all DO_NOT_TRUST_FiddlerRoot certificates in [Trusted Root Certification Authorities]
ā .. Delete all Fiddler certificates existing in other paths
Afterward, if you return to the (Standard Solution) and perform "Reset All Certificates," you can confirm that HTTPS certificates are issued normally.
(Shudder...)
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