Websites and speed
“This Connection Is Not Private” and certificate warnings on a Mac
Safari shows a certificate warning when it cannot confirm the identity of a website. Do not enter passwords or card numbers on that site.
Symptoms
- Safari shows a warning that the connection is not private.
- The Smart Search field shows “Not Secure”.
- Many secure sites show warnings at the same time.
- Only one site, or only one network, shows the warning.
Likely causes
- A wrong date or time on the Mac. A certificate is valid only between two dates. A wrong clock can make a valid certificate look expired.
- An expired or illegitimate certificate. Apple says that Safari warns when the certificate of a website is expired or illegitimate.
- A self-signed certificate. Some internal sites use a certificate that a certificate authority did not issue.
- A network that intercepts connections. A captive portal, a company proxy or security software can show its own certificate.
- An unencrypted site. Safari shows “Not Secure” for a site that does not use HTTPS.
How to check
Click Show Certificate in the warning. Read who issued the certificate, the name it is for, and its dates.
Examine the date, time and time zone on the Mac. Open System Settings > General > Date & Time.
Open other secure sites. If many sites show warnings, the cause is on the Mac or the network.
Join a different network, for example your phone's hotspot. Open the site again. If the warning stops, the first network intercepts connections.
If you are on public Wi-Fi, open any site to show the login page. See Wi-Fi login page does not appear on a Mac.
Show the details of the server certificate from Terminal.
curl -v -I https://example.com
How to fix it
If the date or time is wrong, open System Settings > General > Date & Time. Turn on “Set time and date automatically”.
If the certificate is not trusted, or the name does not match the site, click Cancel. Apple recommends this.
If an internal site uses a self-signed certificate, ask the site owner or administrator about the warning.
If a company proxy or security app inspects connections, ask the administrator for the correct certificate. See Corporate proxy certificates break Terminal tools on a Mac.
Do not enter a password or credit card number on a site that shows a warning.
Questions
Can I click through the warning?
Do not continue on a site that asks for a password or payment. If you continue anyway, Apple says to examine the address, because fraudulent sites can change one or two letters.
Why do many sites show warnings on hotel Wi-Fi?
Many hotel and café networks hold connections until you log in. The login page then answers for other sites. Log in first, then try again.
How do I see if a site is encrypted?
In Safari, choose Safari > Connection Security Details.
Sources
- Apple Support: Avoid fraud by using encrypted websites in Safari on Mac
- Apple Support: If you see a “Not Secure” warning while browsing with Safari
- Apple Support: Set the date and time automatically on your Mac
- curl(1), man page installed with macOS 27.2
Sources checked on 29 October 2026. Man pages are the ones installed with macOS; open one with man <name> in Terminal.