I was trying to create an IOT Hub in the Azure Portal and the UI was displaying errors on the Pricing and scale tier as well as the Subscription selections.

The error details said “Unable to get property ‘value’ of undefined or null reference”

When I attempted to create the IOT Hub using the azure CLI, we got to the real cause of the issue: the subscription was not enabled for “Microsoft.Devices”

To resolve, follow the directions here to register the Microsoft.Devices resource provider on your subscriptions
https://docs.microsoft.com/en-us/azure/azure-resource-manager/resource-manager-common-deployment-errors#noregisteredproviderfound

(Open the subscription, look for the “Resource Providers” option, search for “devices” – click register)

Once you have done this, you will be able to create an IOT Hub.