ERR_CERT_COMMON_NAME_INVALID on Chrome
Why it happens on Chrome
Chrome ignores the legacy commonName field entirely and validates only Subject Alternative Names, so certificates that still work in older tooling fail only in Chrome.
The fix on Chrome
Re-issue the certificate with every hostname listed as a SAN entry — including the bare domain and the www variant. The check below lists the exact SANs the server is presenting.
Is ERR_CERT_COMMON_NAME_INVALID happening on your domain?
The SSL check reports which names the served certificate actually covers, which is the whole answer to this error in one line.
Free, no signup. Runs from outside your network, which is the only way to tell a server fault from a local one.
If that didn't fix it
Chrome has its own failure mode, but ERR_CERT_COMMON_NAME_INVALID has a wider set of causes that apply everywhere. The most common one overall is: the certificate covers the apex domain but not the www hostname, or the reverse.
All causes and fixes for ERR_CERT_COMMON_NAME_INVALID