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TroubleshootingBeginner
Certificate Name Mismatch
Debug certificate name mismatch errors. Understand CN vs SAN, wildcard scope, and common mistakes.
Interactive Demo
What Browsers Check
Certificate says:
www.example.com
vs
Browser connecting to:
shop.example.com
=
ERR_CERT_COMMON_NAME_INVALID
Why This Matters
Name mismatch errors prevent man-in-the-middle attacks. If an attacker presents a valid certificate for attacker.com while you're trying to reach bank.com, the browser blocks it.
#1
Most common SSL error
SAN
What browsers actually check
Easy
To fix once you understand it