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Firefox checks the security certificate for secure websites (those with a padlock 
in the address bar) 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 caused by incorrect time settings.
- Fix your system clock on Windows, macOS, or Linux.
- Learn why some security errors can't be bypassed.
- Troubleshoot special cases like live USBs or virtual machines.
Table of Contents
Step 1 – Check if your error is time-related
If you see an error page such as “Your Computer Clock is Wrong” or “Warning: Potential Security Risk Ahead”, your system clock may be the cause.
How to confirm:
- On the error page, click
- Look for one of these error 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 Windows Start button or press the key.
- Type Date in the search bar.
- Select .
- Click to update from an internet timeserver.
- Make sure your time zone matches your location.
If is disabled or fails:
- Turn off Set time automatically.
- Set the date, time, and time zone manually.
- Click the Windows Start button or press the Windows key .
- In the Start menu, select .
- In Settings, select .
- Go to .
- Below Change date and time, click .
- You can also expand the Time zone dropdown menu.If your system is set to manage the time and time zone automatically, you cannot make manual changes.
- You can also expand the Time zone 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 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, virtual machine, or dual-boot system, your time may reset each time you start the OS. Set it manually every session or configure automatic time sync.
Step 3 – If the problem isn’t your system clock
If your time and time zone are correct, the website’s security certificate may be expired or been misconfigured.
Contact the website owner
If you know the site administrator, let them know the certificate is expired or 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).
