In order to provide the best-in-class encryption to our customers, all Microsoft products/services are in the process of retiring Transport Layer Security (TLS) versions 1.0 and 1.1.
Beginning 8/5/2020, Microsoft Graph Service will stop supporting clients that use TLS 1.0/1.1 in US Government Clouds (Endpoints: https://graph.microsoft.us & https://dod-graph.microsoft.us).
ACTION REQUIRED: Update your Microsoft Graph clients in US Gov Cloud to TLS 1.2 by 8/5/2020 to ensure that you maintain uninterrupted access to Microsoft Graph Service.
Learn more about the update to TLS 1.2 in Microsoft Azure.
Learn more about how this affects your Office 365 account.