MacBook Pro won't open certain websites

Not much to build a response on, here.

• URL of an example?
• Exact text of the Safari error message? (Omitting URL, if that’s sensitive)
• Any add-on anti-malware, add-on anti-virus, add-on adware, add-on VPN client apps, add-on cleaners, or ilk?
• Any commonality across the digital certificates being used at the problematic web sites?
• Does access work when booted in Safe Mode?

If the above doesn’t point to an issue, please download and enable full device access for, and run EtreCheck. Open a new reply here and then press the button that looks like a printed page to get a text input box big enough to paste the hardware and software configuration report here.

See if anything here helps. Safari 13 and High Sierra problem with "a problem repeatedly occurred"

https://discussions.apple.com/thread/251213636

Also working correctly from here, also Mojave10.14.6, though with the older Safari 12.1.2 on the test Mac.

Certain sorts of add-on apps are a common cause of connectivity problems; add-on security apps and add-on cleaner apps.

Also try booting in Safe Mode, and which will temporarily disable various add-ons.

have you found any solution?

secure httpS: connection requires your system TIME be correct within five minutes, and your location

system preferences > Date&Time ...

... be in the correct Time Zone.

¿Are these correct?

what is an example of a web site you can not open?

That site opens fine for me with a valid certificate and shows the lock icon next to the site-name in the URL

Safari 13.1 under MacOS Mojave 10.14.6.