TLS 1.0 Connections to Heroku's Platform API to be Disabled on July 14, 2017
Change effective on 27 June 2017
Connections to Heroku’s Platform API using TLS 1.0 are deprecated. All connections using TLS 1.0 will work until July 14th, at which point TLS 1.0 connections will be disabled. Clients using TLS 1.0 should upgrade to TLS 1.1 or 1.2 to avoid interruptions. This only affects the Platform API and does not affect routing to dynos.
Update: The date has been moved to August 31st