NET::ERR_CERT_DATE_INVALID, what it means and how to fix it
Every certificate has a validity window: a start date and an expiry date. This error means the current moment falls outside that window, either because the site let its certificate expire, the certificate was issued for a future start, or your own device's clock is set wrong and it is your side misreading the window. One of those three is always the cause.
The fix, in order
- Check your device's date and time first. This is the only cause on your side, and it is common: a flat CMOS battery, a manually set clock, or a wrong time zone after travel. Set date and time to automatic, sync, and reload the page.
- Try the site on your phone. If the phone shows the same error, your clock was innocent: the site's certificate really is expired (or not yet valid), and only the site's operator can renew it.
- Look at the certificate dates if you want certainty. Click the “Not secure” indicator or the error's Advanced text and view the certificate; the “valid from / to” dates show whether it has expired or starts in the future.
- Wait, if it is a site you trust. Expired certificates are usually renewed within hours once the operator notices. There is nothing to configure on your side in the meantime.
Do not make a habit of clicking through this warning. Chrome's Advanced → Proceed option exists for controlled situations, like testing your own site. On a real site, an expired certificate means the encrypted connection's identity is unverified; entering passwords or payment details past the warning gives that protection up. Fix your clock, or wait for the site to renew.
If it still happens
If every secure site shows date errors, your device clock or its automatic time sync is broken (or something is deliberately intercepting connections and presenting its own certificates, which the certificate viewer will show: the issuer name will not be a known public authority).
Common questions
Why does a wrong clock break secure sites? The browser compares the current date against the certificate's validity window. A clock set months or years off puts every certificate outside its window, so a single wrong setting produces date errors on site after site.
The certificate expired yesterday. Is the site hacked? Almost certainly not. Expiry is routine maintenance the operator missed; certificates are short-lived now, often 90 days, so lapses are common. It still means identity is unverified until renewed, so treat the connection as untrusted until the site fixes it.
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