MacBook Pro Model A1398 EMC 2512

SSL to TLS:

In 2015, researchers discovered that Secure Socket Layer (SSL) Internet encryption was not nearly as secure as was thought, and needed to be replaced. Internet encryption quickly moved to Transport Layer Security (TLS) which was rapidly deployed across the Internet. Over time, sites tightened requirements for what was acceptable for encryption.

Apple issued Safari version 9 in 10.11 El Capitan version of MacOS, which included TLS encryption. It was later provided by Security Update into the two previous versions of MacOS. 10.10 Yosemite and 10.9 Mavericks, PROVIDED you applied all available software updates.

MacOS versions older than those can not make a lot of secure [httpS:] connections on the Internet, because by todays standards, your proffered SSL encryption is considered inadequate.

If software update does not produce usable results, use this article and the section under "use a Web Browser" to download MacOS 10.11 Yosemite or possibly newer if you have more than 4GB of RAM installed.

This requires a working version of MacOS installed, but the download is not encrypted. if you can not mange how to work-around the encryption of the Apple article to get access, Readers can post the direct download link pulled from the article., or provide guidanace, whoever you prefer.

How to download and install macOS - Apple Support

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FYI, Mac OS X 10.8 Mountain Lion received its last version update in Oct 2013. It is eleven years old, obsolete and no longer supported.

It sounds to me like this will be a network or internet connection security problem.

What are you trying to do with the computer (MacBook Pro 2012?) when you get this error?

Such an error usually indicates a server error with respect to the server's SSL certificate. We'll need to know the exact circumstances of the error before we can offer any useful suggestions.

Regards.