Issue install AADConnect on new server

Question

Attempting to upgrade my AAD Connect servers. I have rebuilt the current staging server with the same hostname and IP with Windows 2019. I verify at least .net 4.8 is installed on the server. I go to install AAD Connect on the server and get the following error.

I check the log and see the following

[11:56:06.474] [ 22] [ERROR] A terminating unhandled exception occurred.
Exception Data (Raw): System.AggregateException: One or more errors occurred. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Online.Deployment.OneADWizard.UI.Controls.PartitionFiltering.LdapTreeviewViewModel..ctor(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateForestPartitionExpanderViewModel(DirectoryConnectionViewModel connection)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateTreeviewForForest(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.LoadTreeviewState(Object obj)
at System.Threading.Tasks.Task.Execute()
--- End of inner exception stack trace ---
---> (Inner Exception #0) System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Online.Deployment.OneADWizard.UI.Controls.PartitionFiltering.LdapTreeviewViewModel..ctor(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateForestPartitionExpanderViewModel(DirectoryConnectionViewModel connection)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateTreeviewForForest(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.LoadTreeviewState(Object obj)
at System.Threading.Tasks.Task.Execute()<---

[11:56:06.493] [ 1] [INFO ] Page transition from "Domain/OU Filtering" [ConfigPartitionFilterPageViewModel] to "Error" [ErrorPageViewModel]
[11:56:06.512] [ 2] [ERROR] A terminating unhandled exception occurred.
Exception Data (Raw): System.AggregateException: A Task's exception(s) were not observed either by Waiting on the Task or accessing its Exception property. As a result, the unobserved exception was rethrown by the finalizer thread. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Online.Deployment.OneADWizard.UI.Controls.PartitionFiltering.LdapTreeviewViewModel..ctor(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateForestPartitionExpanderViewModel(DirectoryConnectionViewModel connection)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateTreeviewForForest(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.OnLoadTask(Object task)
at System.Threading.Tasks.Task.Execute()
--- End of inner exception stack trace ---
---> (Inner Exception #0) System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Online.Deployment.OneADWizard.UI.Controls.PartitionFiltering.LdapTreeviewViewModel..ctor(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateForestPartitionExpanderViewModel(DirectoryConnectionViewModel connection)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.CreateTreeviewForForest(DirectoryConnectionViewModel directory)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.ConfigPartitionFilterPageViewModel.OnLoadTask(Object task)
at System.Threading.Tasks.Task.Execute()<---

[11:56:06.535] [ 1] [INFO ] Page transition from "Error" [ErrorPageViewModel] to "Error" [ErrorPageViewModel]

The current production server is still running without any issues. I am using the same service account to see the domain as the production, yet this staging server seems to be unable to find the domain. The older staging server was Windows 2012 R2.

Answer 1

Hello @Joseph McCants ,

Thanks for reaching out and apologies for the delayed response.

Could please confirm how you updated the server's operating system. Upgrade from 2012 R2 to 2019 in-place or clean installation? Because the previous version of Azure AD connect references (such as Registry Keys, profile path "C:ProgramDataAADConnect", etc..,) are somehow still present on the server, so when you try to install a newer version of Azure AD connect, it somehow communications between ADC and AD are impacted or it cannot either overwrite or replace existing references due to least privilege access of the local account which you used to install AAD connect wizard.

So it's worth doing a clean install of Azure AD connect on the server, and the methods below are detailed. If none of these work, I would suggest contacting Azure support because this would need a more thorough analysis. If you do not have a support plan, please write an email to AzCommunity[at]Microsoft[dot]com referencing this post and your subscription id and we will assist you in obtaining one-time free technical support.

Steps:

1. Completely uninstall the product and all it's components from the server
2. reboot the server
3. Make sure the user that is going to install and configure is a Local Admin on the server
4. Make sure Azure AD connect server required ports as detailed here are opened.
5. Perform a clean install
   -----
   Please "Accept the answer" if the information helped you. This will help us and others in the community as well.