ERR_CERT_DATE_INVALID on Chrome
Why it happens on Chrome
Chrome shows the interstitial with the certificate's exact expiry date, which is the fastest confirmation of whether the clock or the certificate is wrong.
The fix on Chrome
Click Advanced on the warning page to read the reported dates. If the notAfter date is in the future, your clock is wrong; if it is in the past, the certificate genuinely lapsed.
Is ERR_CERT_DATE_INVALID happening on your domain?
The SSL checker returns the exact notAfter date and days remaining for the hostname, which immediately separates 'genuinely expired' from 'your clock is wrong'.
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_DATE_INVALID has a wider set of causes that apply everywhere. The most common one overall is: the certificate expired and auto-renewal silently stopped.
All causes and fixes for ERR_CERT_DATE_INVALID