Symantec, GeoTrust, RapidSSL, Thawte, Verisign certificates will all be distrusted in October 2018 (Affecting) | Firefox Site Compatibility - https://www.fxsitecompat.com/en-CA/docs/2018/symantec-geotrust-rapidssl-thawte-verisign-certificates-will-all-be-distrusted-in-october-2018/