This morning while I was sipping my tea, I pondered life’s most important question: “Why aren’t my users synchronizing from my on-premises Active Directory to my Microsoft Entra ID tenant?”

During my initial Password Hash Sync attempt, my synchronization service account was created, but none of the users synchronized, and the installation service timed out with this error:

“An internal problem has occurred. It appears that you are resuming a scenario that was not completed previously during installation. Please uninstall and try again.”

If the Microsoft Entra Connect (Azure AD Connect) wizard fails to install, the following errors may occur:

An internal problem has occurred. It appears that you are resuming a scenario that was not completed previously during installation. Please uninstall and try again. No registered products found. The synchronization service scheduler is suspended until this setup wizard is closed. Learn more about ‘Scheduler and installation wizard.

To resolve these issues, follow these steps:

In 2019 I answered a question on Stack Overflow about the difference between App Registrations and Enterprise Applications in Azure Active Directory. Two years later I still see questions about the differences between these two terms, as well as questions about how the term “Service Principal” relates to each. The purpose of this blog post is to define these three terms and clarify how they differ from each other.

App Registrations