The Realm of the Verbal Processor

Jarvis's Ramblings

Unknown Computer Bug in Configuration Manager 2012

I just posted an update to this issue. It has been submitted as a Design Change Request to the System Center Product Group.

Today I ran into what I believe to be a bug in the RTM of Configuration Manager 2012. (I have replicated the issue below multiple times in both the RC and RTM.) I’m submitting it on Connect and will update this post if I hear anything back from the product team. BTW…I have mixed feelings writing this post. On one hand it’s exciting to find a bug in a released product (Geek Nirvana). On the other hand, Configuration Manager 2012 is a very solid product that I’m very excited about…I don’t want to make it look bad. Anyway…

I was testing an OSD proof of concept at a client this morning. This is a Configuration Manager 2012 POC and we were deploying Windows 7 32bit over PXE to an HP desktop. I had the following in place:

  • OSD has been working fine.
  • PXE booting is working without problems.
  • I have previously deployed the Win7 image to a different hardware model without issues.
  • The Task Sequence is deployed to a Collection that has “All Unknown Computers” as members via an “Include Rule”

In this instance we were needing to deploy to a new model. I imported the drivers into Configuration Manager and added a new “Apply Driver Package” step into the Task Sequence. I forgot to add the new driver package to a Distribution Point…so when I kicked off the new bare metal deployment to this unknown computer, it naturally failed at the “resolving selected task sequence dependencies” check. I quickly realized what I had overlooked and added the driver package to the DP (and ensured it was source version 2…I was surprised to see that this is STILL an issue.). When I attempted to PXE boot the computer again (the unknown computer that had JUST run the task sequence as an unknown) it failed with the “” error message that typically means that there is no Task Sequence deployment applicable to this computer.


After doing some troubleshooting, I found the following issue…

When the task sequence starts for an unknown computer it creates a new computer object named “Unknown” in the “All Systems” collection. 2_AllSystemsMembership

This computer object has the MAC address and BIOS ID of the previously unknown computer…except that it is now a Known computer…not an Unknown computer…although the System Resource “Unknown Computer” property is set to “1”.


So…my deployment to “All Unknown” computers now fails. This is easy to resolve…simply delete the computer object named “Unknown” and restart the PXE process. But…at best this is an unexpected and undesirable result.

I was able to easily replicate this issue. Here are the steps to replicate the issue:

  1. Add a package to your Task Sequence that has not been distributed to a Distribution Point
  2. Deploy the Task sequence to a collection that includes “All Unknown Computers”
  3. PXE boot a computer that is unknown to Configuration Manager.
  4. Start the task sequence
  5. The Task Sequence fails at the “resolving selected task sequence dependencies” check because of the package in step #1
  6. Find the package that isn’t on a DP and distribute content to the DP (or simply remove it from the Task Sequence).
  7. Attempt to PXE boot the client again and you will get the “” message. “TFTP Download: smsboot\x64\ PXE Boot aborted. Booting to next device…”
  8. In “All Systems” is a computer object named “Unknown” that has the MAC address of the system that was previously unknown. Because it is in the database, it is now a “known” computer…so deployments to “Unknown Computers” won’t pick up this computer any more.

Options to resolve:

  1. Delete the computer object(s) named “Unknown” from All Systems
  2. Add a query rule to the Collection that grabs new computers where the System Resource “Unknown Computer” property = “1”

Note for Option 2: if the TS continues to fail, it will create a second/third/etc object with different resource IDs.

April 6, 2012 - Posted by | ConfigMgr 2012


  1. […] Read the full post: Unknown Computer Bug in Configuration Manager 2012 […]

    Pingback by ConfigMgr 2012 RTM bug to be aware of, with a workaround | April 9, 2012

  2. Jarvis how exactly are you doing this:

    Add a query rule to the Collection that grabs new computers where the System Resource “Unknown Computer” property = “1”

    Which collection are you referring to?


    Comment by Jonathan Vella | April 26, 2012

  3. the collection I referred to is the collection that the task sequence is deployed to…although this will be dependent on collection refresh of that collection, it’s limiting collection (and any other limiting collection until you get back to the all systems collection…which is where the unknown object will appear. quite simply…this is ugly and I wouldn’t recommend it…it simply will take too long for most people.

    Instead…go with the option of deleting the unknown object from the All Systems collection.

    Comment by Jarvis | April 26, 2012

  4. I have this problem too. Deleting the record works fine but would like it to get automated. Unfortunately I don’t understand solution 2 provided here at all.
    What exactly do I need to do?

    Comment by Jesper Walsted | June 3, 2012

  5. So the fix is to manually delete those machine? Is there no news on smarter way fo doing this? It is really a headace for me :(


    Comment by Jesper Walsted | August 16, 2012

  6. Yes…that is the fix unfortunately. This has been put in as a design change request. We can at least HOPE that it makes it into SP1 which should come out reasonably soon…as Windows 8 support is a key component of SP1.

    Comment by Jarvis | August 16, 2012

  7. Thank you for the reply. I guess I could create a SCO runscript that would delete all unknown computers every 1 hour or so untill SP1 is release.

    Comment by Jesper Walsted | August 17, 2012

  8. I dont think this is bug at all. Sccm knows now computer, and object is named unknown.
    There is no need to delete unknown objects (may even crash active task sequences installations).
    Create new collection. Where Limiting collection is set to “All Systems”. Query rule criteria is simple value “System Resource” “Name” is equal to and value is Unknown
    Now deploy task sequence also to new collection. Thats all.
    Collection have some refresh delay, depending your collection and site settings.

    Comment by Niko L | September 27, 2012

  9. I agree that it is technically not a bug…see my follow up post that I mentioned at the top of the post. However…I do not think that this is a good design…hence the reason I submitted it as a Design Change Request. My issue is that this is not a manageable object, and as such it serves to break the normal process of deploying to unknown computers that has been around for a long time. The solution you mentioned is very similar to one of the two options I mentioned in the post. I agree that this will work, but the collection refresh delay does not make this a very desirable option in my opinion (and in the opinion of the clients that I have discussed this issue with).

    Comment by Jarvis | September 27, 2012

  10. Do we know if this change request made it in SP1?

    Comment by Richie T. | January 10, 2013

  11. I’m not sure. I did not see it listed in what is included in SP1, so I doubt it.

    Comment by Jarvis | February 12, 2013

  12. I just deploy to “All Systems” and set it to “PXE and Media only”.

    Comment by Mike | January 2, 2014

  13. Hi, i’m on a new install of sccm 2012 r2 which is only a month old and have come accross this problem today. i guess it wasn’t patched!!

    Comment by Sccm Admin UK | February 3, 2014

  14. I also suffer from this problem. I have so far followed the same path as Niko L and created a collection with a query system resource “name” is equal to Unknown. This way i can monitor it and if neccesary deploy TS’s to these workstations. We are currently imaging a lot of machines atm and I am nervous of the fact some of these could be running task sequences.

    It would be nice if SCCM picked these up with their MININT-XXXX000 name rather than just “Unknown”

    Comment by d4rkcell | April 3, 2014

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: