UGTS Document #35 - Last Modified: 8/29/2015 3:23 PM
IRPStackSize and EventLog error 2011

If you've recently installed or upgraded software, and you're suddenly getting Srv error 2011 in the system event log, you might have a problem with an IRPStackSize that is too low. The IRP Stack refers to the I/O Request Packet Stack. MVP Scott Noone describes it in the SysInternals forum as a stack of buffers used by I/O requests.  An incoming request is placed in the top of the stack, and if the driver needs to delegate to a subdriver, it places a subrequest to the subdriver in the buffer stack just under the first one, and so forth until the request is handled.  If the stack of drivers is deeper than the number of buffers, then the request fails with error 2011.  The depth of the stack is configured in the registry at:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\Parameters\\IRPStackSize (DWORD)

If the value is not present, it defaults to 15. The maximum allowed value is 50, but it should not be set any higher than 31 because of known problems with some network drivers. A safe value is 30. Once the value has been changed, the machine must be restarted to see the changes.

To import the value quickly, download the IRPStackSize.reg file and then rename it from .txt to a .reg extension, and double-click to install the value, then restart the machine.