Certificates & PKI (ADCS) for Beginners

How to Fix SSL Certificate Chain Errors (Missing Intermediate)

curl fails with 'SSL certificate problem: unable to get local issuer certificate' and Python with CERTIFICATE_VERIFY_FAILED, yet the site opens in a browser. The server is sending its certificate without the intermediate. In our own lab (nginx, our own CA) we show what the server sends, why Chromium hides the problem by downloading the missing certificate itself, the one-word fix (fullchain.pem), why adding the certificate to your own laptop or using curl -k isn't a fix, and how to check a chain before your users do.