A
widely used root security certificate, that for IdenTrust DST Root CA
X3, expired on September 30. This is relied on by Let’s Encrypt security
certificates. Although later versions of Mac OS X and macOS have had
replacement root certificates installed, those aren’t in older versions
of Mac OS X.
Please follow the steps below on how it fix this:
1. Go to
https://letsencrypt.org/certs/isrgrootx1.der and download the file (isrgrootx1.der)
2) On your Mac, Go to Applications —> Utilities
3) Select Keychain Access and Open it
4) Select System (all users) or login (current user only)
5) Go to the File Menu and select Import Items
6) Select the file you downloaded isrgrootx1.der and click Open.
7) Find it ("ISRG Root X1") in the list and double click on it.
8) Open the TRUST Section. Set “`When using this certificate:” to “Always Trust”
9) Close the window, which will ask you to verify with your computer login password.
10) Restart your computer. Access caster again.