Install ca-certificates by entering the following commands in the terminal:
sudo apt update sudo apt install ca-certificates
Common CA certificates
Contains the certificate authorities shipped with Mozilla's browser to allow SSL-based applications to check for the authenticity of SSL connections. . Please note that Debian can neither confirm nor deny whether the certificate authorities whose certificates are included in this package have in any way been audited for trustworthiness or RFC 3647 compliance. Full responsibility to assess them belongs to the local system administrator.