What is the most common cause of the 'object reference not set to an instance of an object' error during a Nerdio Join to ARM AVD deployment?

The most common cause is related to incorrect permissions or a missing component in the Nerdio Azure environment. Specifically, the service principal used by Nerdio might lack the necessary rights to create or modify resources within the Azure subscription, such as a virtual network or storage account. Double-check the permissions assigned to the service principal and ensure it has contributor or equivalent access.