Recently I was upgraded wordPress on my local machine, but instead, it turned into a puzzling ordeal marked by a stubborn error message: “Update failed, cURL 60: unable to get local issuer certificate.” The running environment is IIS server with PHP 7.4, I found myself plunged into a troubleshooting saga, with each attempted solution leading to more questions than answers.

The following is my solution steps:

1. Updating Local Certificate File:
   Armed with the error keywords, I scoured Google for solutions and attempted to replace the cacert.pem file within my PHP.INI configuration. Despite my efforts, the problem persisted. Desperate for a workaround, I disabled SSL verification in the WP-CONFIG file, finally the system updated successful.
2. Source code tracking:
   After the update is completed, I am puzzled, try to track the source code through the var_dump method, it took 2 days, the problem still exists.
   
3. Create a test page:
   Recognizing the limitations of source code debugging, I crafted a dedicated test page utilizing cURL to fetch HTTPS content. To my dismay, the issue persisted, leaving me grasping at straws.
   
4. A Last Resort:
   Faced with mounting frustration, I found myself staring blankly at my computer screen. Suddenly, a realization struck me like a bolt from the blue: my system was fortified with security software. With a glimmer of hope, I disabled the protective measures of my security software and reran the test page. Success! The culprit behind the chaos was finally unmasked.

In hindsight, the solution was deceptively simple: beyond updating certificate files, one must also consider the interference of security software when encountering the dreaded “cURL 60: unable to get local issuer certificate” error. This experience serves as a reminder of the intricate dance between technology and human intuition, where perseverance and a keen eye for detail often lead to the most unexpected revelations.