Microsoft is planning to upgrade App Service and Functions infrastructure to Windows Server 2016. This updates paves the way to allow the HTTP/2 protocol for App Service and Functions. For HTTP/2 support they will send communications when it will be available worldwide. The update will began on Monday, December 4, 2017, and continue through January 2018.
What does it mean for the Azure Administrators and End Users?
Most updates can be performed without affecting your services running on the platform’s infrastructure. However it will automatically restart your App Services. This may happen multiple times during the OS patching. Microsoft monitoring team will be monitoring the health of the platform during the rollout.
Test your app in your local environment if you have Windows Server 2016
Alternately you can install IIS in Windows 10 and test your App in Windows 10 environment because Windows 10 shares many components with Windows Server 2016.