SPObject.Resolve()

The option to use Server-to-Server authentication in Dynamics 365 is an important technical approach. It consists of two elements:  1. Azure AD application  2. Dynamics 365 Application user created with the Azure AD application's ID There are many posts about this concept, please do a search and learn it. What I want to show you here is how to solve the problem - Application User form is missing: In order to create an Application user through the web interface, you need to go to: Settings -> Security -> Users -> New: If everything is OK you will see the User's new form and the "Application User" option will be available: If you don't see it, this mean that the form is not Active and you need to active it.  Here are the steps: Step 1: Navigate to the Customise the System: Step 2: Select User entity and choose Forms: Step 3: Select the filter "All Forms" Step 4: Select "Application User" form