Windows logs System event error 21 "The time service has no source of accurate time" when Client is set to NoSync mode.
This article applies to Domain Time Client.
Last Updated: 16 Oct 2018
You have set the Windows Time mode setting (found on the Advanced property page of the Domain Time Client applet) to NoSync,
and the Windows System Event Log reports an Error 21 from the Time-Service: "The time service is configured to use one or more input providers, however,
none of the input providers are available. The time service has no source of accurate time." whenever the Windows Time service starts.
When set to NoSync, The NtpClient time provider section of Windows Time is disabled. On physical machines that are domain members, the
VMICTimeProvider also fails during startup (as there is no hypervisor present). Windows Server therefore erroneously concludes
that the time service has no source of time, even though it is correctly set to NoSync mode.
The default behavior for Domain Time version 5.2 is to disable the Windows Time service, since all of its functionality is handled by Domain Time.
However, older versions of Domain Time needed to set the Windows Time service into NoSync mode on domain controllers and some cluster servers
so that they could respond to NT5DS-mode authenticated time requests or fulfill start up dependencies. NoSync mode allows the NtpServer section of
the Windows Time service to run, but permits the NtpClient portion of the service to be disabled so that Domain Time Client can synchronize the local
With the introduction of Hyper-V support, Microsoft added an additional time provider to Windows Time, the VMICTimeProvider. This assists Windows
Time in sychronizing with the Hyper-V host. This provider is enabled by default, even when installed on systems not running Hyper-V. Typically,
this causes no issues as the provider simply fails to load during startup on non-Hyper-V systems. However, when a Server operating system is installed on
a physical machine that is a member server or domain controller, a Time-Service error 21 is logged in the Windows Event System log if NtpClient time provider is
disabled, even if the service is in NoSync mode.
You may address this error in several ways:
- Install Domain Time Server on any Domain Controller. Change the Windows Time mode setting on the Advanced tab of any other clients to Disabled
(If the machine is a Server 2003 cluster server, see the Cluster Service section
of the documentation). This is the recommended environment for running Domain Time version 5.2.
- Disable the VMIC time provider. Use RegEdit to change the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\VMICTimeProvider\Enabled
value to 0.
- Ignore it. The error doesn't prevent the synchronization of time.