Check your device clock first
Google Chrome specifically recommends verifying the computer or phone's date and time for this error. Certificates have defined validity periods, so an incorrect clock can make a valid certificate appear expired or not yet valid.
If the date and time are correct
If several devices with accurate clocks show the error, the website is more likely at fault: its certificate may have expired, may not yet be valid, or the CDN may be presenting the wrong certificate.
How can you distinguish a local issue from a website issue?
- Check whether multiple HTTPS websites are affected.
- Try the same page on your phone using mobile data.
- If one domain fails everywhere, inform the website owner.
- Use the website checker and read Your connection is not private.
If you manage the website
Inspect the certificate's validity dates, hostname, certificate chain and the certificate actually served by the public CDN or reverse proxy. With automated renewals, verify the new certificate was deployed to every instance.
How it differs from ERR_SSL_PROTOCOL_ERROR
NET::ERR_CERT_DATE_INVALID is a specific certificate-related signal. ERR_SSL_PROTOCOL_ERROR is a broader TLS problem.
Frequently asked questions
Is the website certificate always to blame?
No. An incorrect date, time or timezone on your device can produce the same error.
What if the clock is correct?
Compare another device and network. If the same domain fails everywhere, the owner should check the publicly served certificate.
Can I simply proceed to the page?
We do not recommend it for sensitive pages. Find the cause of the warning first.