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Firefox checks a website’s security certificate (those with addresses starting with https://) to make sure it’s valid and hasn’t expired. If your computer’s date, time, or time zone is incorrect, Firefox may show a security warning instead of loading the page.
This article helps you:
- Identify if your error is time-related.
- Correct your system clock settings on Windows, macOS, and Linux.
- Understand why some errors can’t be bypassed.
- Address edge cases like live USB systems or virtual machines.
Table of Contents
Step 1 – Check if your error is time-related
If you see an error page like "Your Computer Clock is Wrong" or "Warning: Potential Security Risk Ahead", the issue may be your system clock. How to confirm:
- On the error page,
- Look for one of these codes:
- SEC_ERROR_EXPIRED_CERTIFICATE
- SEC_ERROR_EXPIRED_ISSUER_CERTIFICATE
- SEC_ERROR_OCSP_FUTURE_RESPONSE
- SEC_ERROR_OCSP_OLD_RESPONSE
- MOZILLA_PKIX_ERROR_NOT_YET_VALID_CERTIFICATE
- MOZILLA_PKIX_ERROR_NOT_YET_VALID_ISSUER_CERTIFICATE
Step 2 – Set your system clock to the correct time
- Click the button or press the key.
- Type Date in the search bar.
- Select .
- Click to update from an internet time server.
- Make sure your time zone matches your location.
If is disabled or fails:
- Turn off .
- Manually set the correct date, time, and time zone.
- Click the button or press the Windows key .
- In the Start menu, select .
- In Settings, select .
- Go to .
- Below , click on
- Youy can also expand the dropdown menu.If your system is set to manage the time and time zone automatically, you cannot make manual changes.
- Youy can also expand the dropdown menu.
- If you are done with your changes, close the Settings window.
- From the Start Screen, click the Desktop tile.
- Select from the .
- Click on Clock, Language, and Region and then Date and Time.
- Click the or button.
- To confirm your changes click .
- Click the Windows Start button or press the Windows key .
- Click .
- Click on Clock, Language, and Region and then Date and Time.
- Click the or button.
- To confirm your changes click .
- Click the Apple menu and select .
- In the System Preferences window, click on Date & Time.
- Disable Set date and time automatically,
- Manually enter the date and time.
- Click to confirm your changes.
Special cases – live USB, virtual machines, dual-boot systems
If you use a live USB or virtual machine, your time may reset every time you start the system. You’ll need to set it manually each session or configure your OS to sync time automatically.
Step 3 – If the problem isn’t your system clock
If your time and time zone are correct, the website’s security certificate may have expired or been misconfigured.
Contact the website owner
If you know the site administrator, tell them the certificate has expired or is invalid. They may need to renew or fix it.
Why you can’t always override these errors
Firefox’s security checks are automated—Firefox doesn’t decide which sites are “safe” based on reputation or government ownership. If a certificate is expired or invalid, Firefox will block the page to protect your privacy and data.
In most cases, these blocks can’t be bypassed for expired certificates because they present real security risks (like allowing attackers to intercept your connection).
Quick checklist before trying again
- ✅ System date and time are correct.
- ✅ Time zone matches your location.
- ✅ For live USB/VM users: time sync is configured.
- ✅ Website’s certificate isn’t expired (contact site owner if unsure).
