When the problem follows a specific browser.
WHAT IT USUALLY MEANS
The certificate is fine and something local to that browser or machine is interfering.
COMMON CAUSES
A cached old certificate or redirect in that browser. Test in a private window. An extension intercepting traffic Antivirus or security software performing HTTPS inspection with its own certificate A corporate network doing the same An outdated browser with an old trust store The computer's clock being wrong, which affects all browsers on it but may be noticed in one
WHAT TO DO
- Test in a private window in the same browser.
- Test in a different browser on the same machine.
- Test on a different network, such as mobile data.
- Disable extensions temporarily.
- Check the system clock.
IF IT AFFECTS ONLY YOUR MACHINE
The site is fine for visitors. Fix your machine rather than changing the server.
IF A VISITOR REPORTS IT
Ask them to test in a private window and on another device before assuming the site is at fault.
