A final reminder that if you experience a disruption of service accessing ArcGIS Online after April 16th, please refer to our extensive support guidance for determining how to get up and running in the most effective manner for various products and deployment scenarios – https://support.esri.com/en/tls
We are hopeful disruptions are minimal based on the extensive notifications we have provided to our customer base (thanks for your understanding of all those notices). To keep our customers secure, periodic changes like this are a necessary part of hosting an enterprise-class offering such as ArcGIS Online. Along similar lines, new ArcGIS Enterprise 10.7 deployments utilize only TLS 1.2 and also only allow HTTPS communications by default.
Additional security advancements will continue to be incorporated over time as discussed here.
– Esri Software Security & Privacy Team