AAD Support at Pax8 won't help, says this is a server issue and to open a case with Microsoft Server support. I've tried 3 different version of AAD Sync install on Server 2019. They install fine but during the configuration, it halts at Synchronization Service.

Event log shows
Event 906, ADSyncBootstrap
EnableADSyncBootstrapLocalDBInstance: Error while attempting to enable local db instance. Details: System.InvalidOperationException: LocalDB ShareInstance operation failed.
at Microsoft.Azure.ActiveDirectory.Synchronization.Framework.SqlLocalDbAdapter.ShareInstance(String instanceName, String sidOwner)
at Microsoft.Azure.ActiveDirectory.Synchronization.Framework.SqlLocalDbAdapter.CreateNewSQLLocalDBInstance(Version targetInstanceVersion, String targetInstanceName, String syncAdminsGroupUserName, String dbAdminUserAccount)
at Microsoft.Azure.ActiveDirectory.ADSyncBootstrap.ADSyncBootstrapManagementService.EnableADSyncBootstrapLocalDBInstance(Version targetInstanceVersion, String targetInstanceName, String syncAdminsGroupUserName, String dbAdminUserAccount)
MSSQLLocalDB\error.log shows success.
Trace log shows:
[09:51:36.466] [ 36] [INFO ] ServiceControllerProvider: InvalidOperationException on serviceController.Status property means the service ADSync was not found
[09:51:36.467] [ 36] [INFO ] ServiceControllerProvider:CreateService - serviceName:ADSync, username:DOMAIN\ADSyncMSA392b1$, assemblyPath:C:\Program Files\Microsoft Azure Active Directory Connect\ADSyncBootstrap.exe
[09:51:39.099] [ 36] [INFO ] ServiceControllerProvider: Processing StartService request for: ADSync
[09:51:39.099] [ 36] [VERB ] ServiceControllerProvider: Initial service status: Stopped
[09:51:39.099] [ 36] [VERB ] ServiceControllerProvider: Starting service and waiting for completion.
[09:51:39.550] [ 36] [INFO ] ServiceControllerProvider: StartService status: Running
[09:51:40.027] [ 36] [INFO ] ServiceControllerProvider: processing StopService request for: ADSync
[09:51:40.027] [ 36] [VERB ] ServiceControllerProvider: Initial service status: Running
[09:51:40.027] [ 36] [VERB ] ServiceControllerProvider: stopping service and waiting for completion.
[09:51:40.279] [ 36] [INFO ] ServiceControllerProvider: StopService status: Stopped
[09:51:40.279] [ 36] [INFO ] ServiceControllerProvider: Processing StartService request for: ADSync
[09:51:40.279] [ 36] [VERB ] ServiceControllerProvider: Initial service status: Stopped
[09:51:40.279] [ 36] [VERB ] ServiceControllerProvider: Starting service and waiting for completion.
[09:51:40.684] [ 36] [INFO ] ServiceControllerProvider: StartService status: Running
[09:52:01.701] [ 36] [INFO ] ServiceControllerProvider: service ADSync exists
[09:52:01.701] [ 36] [INFO ] ServiceControllerProvider: processing StopService request for: ADSync
[09:52:01.701] [ 36] [VERB ] ServiceControllerProvider: Initial service status: Running
[09:52:01.701] [ 36] [VERB ] ServiceControllerProvider: stopping service and waiting for completion.
[09:52:01.956] [ 36] [INFO ] ServiceControllerProvider: StopService status: Stopped
[09:52:01.956] [ 36] [INFO ] ServiceControllerProvider:DeleteService - serviceName:ADSync
[09:52:11.969] [ 36] [INFO ] ServiceControllerProvider: InvalidOperationException on serviceController.Status property means the service ADSync was not found
[09:52:11.969] [ 36] [INFO ] ServiceControllerProvider:DeleteService successful - serviceName:ADSync
[09:52:11.985] [ 36] [INFO ] ServiceControllerProvider: processing StopService request for: ADSync
[09:52:11.986] [ 36] [WARN ] ServiceControllerProvider: StopService failed to stop service (ADSync), attempt (1).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StopService(String serviceName, TimeSpan timeout)
[09:52:11.986] [ 36] [WARN ] ServiceControllerProvider: StopService failed to stop service (ADSync), attempt (2).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StopService(String serviceName, TimeSpan timeout)
[09:52:11.987] [ 36] [WARN ] ServiceControllerProvider: StopService failed to stop service (ADSync), attempt (3).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StopService(String serviceName, TimeSpan timeout)
[09:52:11.987] [ 36] [WARN ] ServiceControllerProvider: StopService failed to stop service (ADSync), attempt (4).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StopService(String serviceName, TimeSpan timeout)
[09:52:11.987] [ 36] [WARN ] ServiceControllerProvider: StopService failed to stop service (ADSync), attempt (5).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StopService(String serviceName, TimeSpan timeout)
[09:52:11.987] [ 36] [WARN ] ServiceControllerProvider: StopService failed to stop service (ADSync), attempt (6).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StopService(String serviceName, TimeSpan timeout)
[09:52:11.988] [ 36] [WARN ] ServiceControllerProvider: StopService failed to stop service (ADSync), attempt (7).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StopService(String serviceName, TimeSpan timeout)
[09:52:11.988] [ 36] [ERROR] ServiceControllerProvider: StopService unable to stop service (ADSync). The system event log may contain more details for this issue.
[09:52:11.988] [ 36] [INFO ] ServiceControllerProvider: Processing StartService request for: ADSync
[09:52:11.988] [ 36] [WARN ] ServiceControllerProvider: StartService failed to start service (ADSync), attempt (1).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StartService(String serviceName, TimeSpan timeout, Boolean verifyStart, String[] args)
[09:52:11.988] [ 36] [WARN ] ServiceControllerProvider: StartService failed to start service (ADSync), attempt (2).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StartService(String serviceName, TimeSpan timeout, Boolean verifyStart, String[] args)
[09:52:11.988] [ 36] [WARN ] ServiceControllerProvider: StartService failed to start service (ADSync), attempt (3).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StartService(String serviceName, TimeSpan timeout, Boolean verifyStart, String[] args)
[09:52:11.989] [ 36] [WARN ] ServiceControllerProvider: StartService failed to start service (ADSync), attempt (4).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StartService(String serviceName, TimeSpan timeout, Boolean verifyStart, String[] args)
[09:52:11.989] [ 36] [WARN ] ServiceControllerProvider: StartService failed to start service (ADSync), attempt (5).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StartService(String serviceName, TimeSpan timeout, Boolean verifyStart, String[] args)
[09:52:11.989] [ 36] [WARN ] ServiceControllerProvider: StartService failed to start service (ADSync), attempt (6).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StartService(String serviceName, TimeSpan timeout, Boolean verifyStart, String[] args)
[09:52:11.989] [ 36] [WARN ] ServiceControllerProvider: StartService failed to start service (ADSync), attempt (7).
Exception Data (Raw): System.InvalidOperationException: Service ADSync was not found on computer '.'. ---> System.ComponentModel.Win32Exception: The specified service does not exist as an installed service
--- End of inner exception stack trace ---
at System.ServiceProcess.ServiceController.GenerateNames()
at System.ServiceProcess.ServiceController.get_ServiceName()
at System.ServiceProcess.ServiceController.GenerateStatus()
at System.ServiceProcess.ServiceController.get_Status()
at Microsoft.Online.Deployment.Framework.Providers.ServiceControllerProvider.StartService(String serviceName, TimeSpan timeout, Boolean verifyStart, String[] args)
[09:52:11.990] [ 36] [ERROR] ServiceControllerProvider: StartService unable to start service (ADSync). The system event log may contain more details for this issue.
[09:52:11.991] [ 36] [ERROR] PerformConfigurationPageViewModel: Caught exception while installing synchronization service.
Exception Data (Raw): System.Exception: Unable to install the Synchronization Service. LocalDB powershell operation failed on ADSync Bootstrap service: Enable-ADSyncBootstrapLocalDBInstance. Additional information may be found in the sql database error log files 'C:\Users\ADSyncMSA392b1$\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances\MSSQLLocalDB\error.log'. Please see the Application and System event logs for additional details. ---> System.InvalidOperationException: LocalDB powershell operation failed on ADSync Bootstrap service: Enable-ADSyncBootstrapLocalDBInstance. Additional information may be found in the sql database error log files 'C:\Users\ADSyncMSA392b1$\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances\MSSQLLocalDB\error.log'.
at Microsoft.Azure.ActiveDirectory.Synchronization.Setup.SynchronizationServiceSetupTask.InstallCore(String logFilePath, String logFileSuffix)
at Microsoft.Azure.ActiveDirectory.Synchronization.Framework.ActionExecutor.ExecuteWithSetupResultsStatus(SetupAction action, String description, String logFileName, String logFileSuffix)
at Microsoft.Azure.ActiveDirectory.Synchronization.Setup.SetupBase.Install()
--- End of inner exception stack trace ---
at Microsoft.Azure.ActiveDirectory.Synchronization.Setup.SetupBase.ThrowSetupTaskFailureException(String exceptionFormatString, String taskName, Exception innerException)
at Microsoft.Azure.ActiveDirectory.Synchronization.Setup.SetupBase.Install()
at Microsoft.Online.Deployment.OneADWizard.Runtime.Stages.InstallSyncEngineStage.ExecuteInstallCore(ISyncEngineInstallContext syncEngineInstallContext, ProgressChangedEventHandler progressChangesEventHandler)
at Microsoft.Online.Deployment.OneADWizard.Runtime.Stages.InstallSyncEngineStage.ExecuteInstall(ISyncEngineInstallContext syncEngineInstallContext, ProgressChangedEventHandler progressChangesEventHandler)
at Microsoft.Online.Deployment.OneADWizard.UI.WizardPages.PerformConfigurationPageViewModel.ExecuteSyncEngineInstallCore(AADConnectResult& result)
Server is fully updated and restarted. TLS 1.2 is explicitly enabled.
Have completely uninstalled, restarted, reinstalled each time, same error.
Reviewed the following:
https://learn.microsoft.com/en-us/answers/questions/1334042/error-when-trying-to-install-azure-active-director?cid=kerryherger
https://learn.microsoft.com/en-us/answers/questions/1374127/cant-install-microsoft-azure-active-directory-conn
https://community.spiceworks.com/t/adconnect-fails-to-install/828016
https://community.spiceworks.com/t/azure-ad-connect-failing-to-install/782353
https://www.reddit.com/r/MSFTAzureSupport/comments/1dlrace/microsoft\_azure\_ad\_connect\_entra\_connect\_setup/