Microsoft Forefront Unified Access Gateway 2010 Direct Access machine crashes with stop code 0xD1

Applies to: Forefront Unified Access Gateway 2010Microsoft Forefront Unified Access Gateway 2010 Service Pack 1


A Microsoft Forefront Unified Access Gateway 2010 (UAG) computer configured for Direct Access crashes with the stop code 0xD1 and the following event is logged:

Log Name:      System
Source:        Microsoft-Windows-WER-SystemErrorReporting
Date:          xxxxxx
Event ID:      1001
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      xxxxxxx
The computer has rebooted from a bugcheck.  The bugcheck was: 0x000000d1 (0x00000001000000f8, 0x0000000000000002, 0x0000000000000000, 0xfffff88000e01bd0). A dump was saved in: C:\Windows\MEMORY.DMP.


This can occur due to a race condition.


The following workarounds are available for this problem:

Workaround 1 (recommended):

Uncheck the Qos Packet scheduler on all interfaces on the machine experiencing the issue.

The Qos Packet scheduler is a component which is relevant only if you use Quality of Service (QoS) to control the flow of network traffic.

If you do not use QoS then it is safe to uncheck it.

To disable the Qos Packet Scheduler, follow these steps for each adapter installed.

1.     Click Start, and then click Control Panel.

2.     In Classic View, click Network and Sharing Center.

3.     Select Change adapter settings

4.     Right-click the network entry where you want to uncheck the QoS Packet Scheduler, and then click Properties.

5.     Uncheck QoS Packet Scheduler, and then click OK.

For information about enabling QoS marking and the QoS Packet Scheduler service, see the Introduction to Microsoft Office Communications Server 2007 Technical Reference.

Reboot the computer.

Workaround 2:

If the previous workaround is not applicable, e.g. because QoS is needed, you can disable NDIS integration by running the following command:

netsh tmg set global name=disablendisregistration value=1 persistent

Reboot the computer.


This workaround of disabling NDIS integration (netsh tmg set global name=disablendisregistration value=1 persistent ) may occasionally break Direct Access (specifically 6to4) in certain cases. This is due to a boot time timing issue, and a solution for this is to restart the IP Helper service 15 minutes after booting (e.g. restart the IP Helper service via a script scheduled from Task Scheduler). 

This scheduled task can be configured to run 15 minutes after reboot and restart the iphelper service by running a batch file with the following content:

net stop iphlpsvc
net start iphlpsvc

Take this into account when you use this workaround as failure to do this may cause connectivity problems.