How to Troubleshoot Group Policy Processing Errors in an Active Directory Domain

Members of an Active Directory (AD) domain can experience problems applying Group Policy for a number of reasons. This article discusses some of the more common ones and provides guidelines for troubleshooting the underlying issues.
 
General Troubleshooting
The first step in troubleshooting these issues should be to determine their extent. If only one machine is unable to process Group Policy, the problem likely stems from a malfunction or misconfiguration of that machine. If the issue is more widespread, the problem may exist on a domain controller (DC) or in AD itself.

If only one machine is affected, run gpupdate /force on the affected machine before troubleshooting further. This ensures that the failure wasn't caused by a temporary network issue that has since been resolved.

When a machine is unable to process Group Policy, it typically generates one or more Userenv errors in its Application log. Common event ID numbers include 1030, 1053, 1054, and 1058. The descriptions of the particular errors on an affected machine should give some idea of the underlying issue.

DNS Issues
Perhaps the most common cause of Group Policy failures - and numerous other AD issues - is a name-resolution problem. If the Userenv errors on an affected machine include the phrase "Network path not found" or "Cannot locate a domain controller," DNS may be to blame. The following are a few tips for troubleshooting this type of issue:

• Open a command prompt on an affected machine and run nslookup domain (nslookup mydomain.local, for example). This command should return the IP addresses of all DCs in the domain. If any other addresses are returned, there are likely invalid records in DNS. The nslookup command can also be used to resolve the names of individual DCs to their IP addresses.
• Run ipconfig /all on an affected machine and verify that it is configured to use only internal DNS servers. Using the wrong DNS servers is the main cause of DNS issues in a domain, and it is easily remedied. All domain-joined machines must use only internal DNS servers, which are typically DCs.
• If the affected machine appears to be using the correct DNS servers, check the DNS console on a DC to verify that the proper records exist. Verify that each DC has two host (A) records in the domain forward lookup zone: one with the DC's hostname and one with the name "(same as parent folder)". Both records should include the IP address of the DC.
• Once a DNS problem has been resolved, run ipconfig /flushdns on any affected machines. This will purge any invalid data from the resolver cache on those machines.

Secure Channel Issues
This type of issue occurs when a domain-joined machine's locally stored computer account password does not match its password in AD. A secure-channel problem prevents a machine from authenticating with a DC. It often manifests itself as an "Access denied" error whenever that machine attempts to access domain resources, including Group Policy updates. Of course, not all "Access denied" events are due to secure-channel issues, but if an affected machine has Userenv errors in its Application log with "Access denied" in their description, the secure channel is worth testing.

• The nltest command can be used to test (and reset, if necessary) the secure channel on a domain member.
• The netdom command can also test and reset the secure channel.
• The Test-ComputerSecureChannel PowerShell cmdlet provides another means to test or reset the secure channel.
• Removing the affected machine from the domain, resetting its AD computer account, and rejoining it to the domain will reset its secure channel. This is not always feasible, however.

​​​​Problems with SYSVOL
Group Policy template files are stored in the SYSVOL share on all DCs in the domain. The SYSVOL data is replicated among DCs using either the File Replication System (FRS) or Distributed File System Replication (DFSR). If the SYSVOL share is not present on a DC, this typically indicates a problem with SYSVOL replication.

Clock Skew
By default, Kerberos authentication requires that domain-joined machines' clocks be within five minutes of each other. Exceeding this threshold causes authentication failure, which in turn prevents processing of Group Policy. Everything in the domain should be configured to synchronize its clock with AD, with one exception. The DC which holds the PDC Emulator FSMO role is the authoritative time source for the domain. Therefore, it is the only machine in a domain which should synchronize with an external source, such as a public NTP server.

More information on configuring the Windows Time service is available here.

Missing Group Policy Files
One or more Group Policy files may have been deleted from their storage location in SYSVOL. Check this by browsing to SYSVOL\domain\Policies in File Explorer and looking for specific files mentioned in Userenv errors. The files for each GPO are located in a subfolder of the Policies folder. Each subfolder is named after the hexadecimal globally unique identifier (GUID) of the GPO whose files it contains.

If policy files are found to be missing from all DCs, they can be restored from a backup. If the Default Domain Policy or Default Domain Controller Policy files are missing and no backup is available, the dcgpofix command can restore both policies to their default settings.

More information about dcgpofix can be found here.