“Your clock is ahead” or “behind”: what it means and how to fix it

What this message means

Every website certificate is valid only for a set period. The browser checks this against the clock on your device. If the date is wrong, every certificate looks expired or not yet valid, and sites with https:// addresses stop opening.

• Chrome shows the heading “Your clock is ahead” (the date on your device is in the future) or “Your clock is behind” (the date is in the past). Below it is the sentence “A private connection to … can’t be established because your computer’s date and time (…) are incorrect.” and the code NET::ERR_CERT_DATE_INVALID. Chrome recognizes a wrong clock by comparing it with the time it gets from the internet.
• Firefox shows “Your Computer Clock is Wrong” and asks you to set the current date, time and time zone in your system settings.
• When the browser cannot tell on its own that the clock is to blame, it shows the usual certificate warning: Chrome “Your connection is not private” with the same code, and Firefox “Be careful. Something doesn’t look right.” with the code SEC_ERROR_EXPIRED_CERTIFICATE or MOZILLA_PKIX_ERROR_NOT_YET_VALID_CERTIFICATE.

If Chrome shows an “Update date and time” button below the message, it opens the date and time settings of your system. After fixing the clock, reload the page.

Windows 11

1. Select “Start” → “Settings” → “Time & language” → “Date & time” (or press Windows+I to open Settings).
2. Turn on “Set time automatically” and “Set time zone automatically”. Windows then sets the date and time by itself.
3. If you prefer to set the time by hand, turn off “Set time automatically”, select “Change” next to “Set the date and time manually”, enter the correct values and confirm.

Mac

1. Open “System Settings”, click “General” in the sidebar, then click “Date & Time”.
2. Turn on “Set time and date automatically”. If your Mac asks for a time server, click “Set”, enter a network time server for your region and click “Done”.
3. Turn on “Set time zone automatically using your current location”.

iPhone and Android phones

• iPhone: go to “Settings” → “General” → “Date & Time” and turn on “Set Time Automatically”. Your phone needs an internet connection.
• Android, Clock app: open “Clock”, tap “More” → “Settings” → “Change date and time” and turn on “Automatic date and time” and “Automatic time zone”. On phones with a different clock app, similar switches are in Settings, in the date and time section.

After the change, close the tab with the warning and open the site again.

If it is your website: the certificate may really have expired

The clock message is about the visitor’s device, not the website. But if the date warning appears on different computers and phones with the correct date, your site’s certificate has expired. Chrome then shows “Your connection is not private” with the code NET::ERR_CERT_DATE_INVALID, and after you click “Advanced”, how many days ago the certificate expired. Firefox shows the code SEC_ERROR_EXPIRED_CERTIFICATE.

1. Check the certificate’s expiry date on a device with a correct clock. We explain how on the page How to check when a certificate expires.
2. Generate a new certificate for the same addresses in the generator and upload it to the same place following the guide for your hosting. The full fix, step by step, is in the guide SSL certificate expired.
3. Save the certificate in your freessl.pl account. We send you an email reminder after two thirds of its validity and a second one a week before it ends.