Require Secure HTTPS Connections (Critical Update)
Where: This change applies to Lightning Experience, Salesforce Classic, and all versions of the Salesforce app in all editions.
When: This critical update is activated automatically on January 30, 2020 in sandboxes and May 1, 2020 in production orgs.
How: We recommend that you test this update in a sandbox or Developer Edition org before enabling it in your Salesforce production org. Ensure that your environment is setup to support HTTPS connections and update all bookmarks and links with the HTTP prefix before the auto-activation date.
To activate this critical update before the auto-activation date, from Setup, in the Quick Find box, enter Critical Updates, then select Critical Updates. For Require Secure HTTPS Connections, click Activate.