How to fix the error 'SSL certificate problem: certificate has expired' from closing projects on Exploratory Public on Mac

If you see an Error Report dialog with an error message 'SSL certificate problem: certificate has expired' at closing project on Exploratory Public running on macOS Mojave or older, please read on.

Cause of the Error

On September 30, a root SSL certificate that exploratory.io depends on expired. For more detail on the expiration of the root SSL certificate, please take a look at this page.

This expiration affected git command on macOS Mojave or older, which Exploratory Public uses to publish projects to exploratory.io at closing of projects.

How to Fix It

By removing the expired root SSL certificate, DST Root CA X3, from the list of trusted root SSL certificates, this error will stop happening.

(We recommend backing up the file /etc/ssl/cert.pem before this operation.)

Open /etc/ssl/cert.pem with an editor. The beginning of the lines to remove starts with the following lines.

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            44:af:b0:80:d6:a3:27:ba:89:30:39:86:2e:f8:40:6b
    Signature Algorithm: sha1WithRSAEncryption
        Issuer: O=Digital Signature Trust Co., CN=DST Root CA X3
        Validity
            Not Before: Sep 30 21:12:19 2000 GMT
            Not After : Sep 30 14:01:15 2021 GMT
...

And it ends with the following lines.

...
JDGFoqgCWjBH4d1QB7wCCZAA62RjYJsWvIjJEubSfZGL+T0yjWW06XyxV3bqxbYo
Ob8VZRzI9neWagqNdwvYkQsEjgfbKbYK7p2CNTUQ
-----END CERTIFICATE-----

Remove the lines in this range and save the file. Now your Exploratory Publish should be able to close the project without the error.

Of course, you can also upgrade your macOS to Catalina or newer to resolve this issue.