“This certificate was signed by an untrusted issuer” problem after updating to Mac OS.

This certificate was signed by an untrusted issuer” problem after updating to Mac OS.

Your computer has expired certificates.
To solve this make the following actions:

  1. Applications > Utilities > Keychain Access.
  2. Select
    a) Keychain: Login and
    b) Category: Certificates
  3. Scroll each certificate and if it has expired delete it.

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