Google had announced that Chrome would begin distrusting certificates issued by Symantec Corporation’s PKI and the decision is followed by other major browsers.
These are the certificates by Thawte, VeriSign, Equifax, GeoTrust, and RapidSSL that are issued before 1st of December 2017.
And, as the distrust is in effect and visitors are displayed an error on these websites (like ERR_CERT_SYMANTEC_LEGACY), Uptime Robot’s SSL monitoring feature now also considers these errors as a reason for downtime.
Such downtimes are displayed as “Distrusted Certificate” in the dashboard and the feature is live in the Pro Plan.