Switch from Bios to UEFI seamless using Configuration Manager TS in 6 simple steps

This solution has been created and tested by a colleague of mine Johan Schrewelius, he has done most of the work so I cannot give him enough credit for this. We have been using it for a while now and it works great, it is 100% unsupported 😉 as we change values on a read-only variables in the TS.

If you are using Configuration Manager 1610 or later there is now a supported built-in way to do this. https://docs.microsoft.com/en-us/sccm/osd/deploy-use/task-sequence-steps-to-manage-bios-to-uefi-conversion

1         Background

The release of Windows 10 in combination with steadily increasing security demands means an operating system upgrade, or fresh install, today also includes security measures that not long ago where sort of luxury or only experimental.

Two major such are UEFI and Secureboot; a significant challenge as not even Configuration Manager 1602 supports a seamless transformation from Legacy Bios to UEFI.

This post describes our method of achieving the desired; one (1) Task Sequence that starts in Legacy mode and results in an UEFI configured computer with Secureboot enabled. A script and files for configuring HP computers have been included as example. No PXE boot is required as we boot from the local disk when we reboot. This is a short flow of what happens:

1. Configure Bios to UEFI and Secureboot using the tool for the vendor/model

2.Then we partition the local disk to GPT and format it

3.Copy an exported Boot image from a package to the local disk

4.Change the value for a read-only variable _SMSTSServiceStart using the 1E tool

5.Restart the computer and boot to the local installed Operating System

6.Change the second read-only variable _SMSTSBootUEFI to true and then the TS and all builtin steps for formatting will see that it is a machine running UEFI.

In the Task Sequence it looks like this:



To implement our solution, you need to download Legacy2Uefi as well as TSEnv2.exe from 1E (http://info.1e.com/website-freetools-1e-tsenv2) 1E has been generous enough to share this powerful tool with us, and we cannot thank them enough.

2         Obstacles

There are two major obstacles that prevents us from achieving our goal using a standard TS.

Firstly, we will not be able to apply a boot-image nor an operating system to a GPT disk on what is detected as a MBR System.

Secondly, if we (which we nevertheless will do later) apply bootable media to disk by running a script we will not be able to restart the computer in a controlled fashion as built-in controls (smsboot.exe) will prevent this based on inconsistencies in TS configuration, i.e.  the TS-variable “_SMSTSServiceStartType” not being set to auto, which is required to allow rebooting to an installed operating system. Unfortunately, this variable is read-only and we cannot modify it using supported means. But what if we use unsupported means……

3         Read-only TS-variables < TSEnv2.exe

It is usually not recommended to use unsupported means; this however could be the time when circumstances call for it? TSEnv2.exe is able to modify read-only TS-variables and since that is what stands between us and a successful Legacy to UEFI transformation, that’s exactly what we are going to do.

TSEnv2.exe comes in both 32- and 64-bit versions, it is also depending on native Configuration Manager libraries, at least tscore.dll. This makes it reasonable to include it in our boot images using OSDInjection.

4         OSDInjection

To include TSEnv2.exe in already existing, as well as in new, boot images do the following on the primary site server or CAS that “owns” the images. And yes you can use the MDT feature as well to include the files when you create a new MDT Boot Image instead.

  1. Localize your ..\OSD\bin directory.
  2. Copy the corresponding version of TSEnv2.exe to the x64 as well as the i386 subfolder.
  3. Once the files have been copied we need to tell ConfigMgr to actually include them the next time an image is created or updated. This is done by editing “osdinjection.xml” which is found in ..\bin\x64:

Remark – there’s only one osdinjection.xml, not one per architecture.

Remember to Backup osdinjection.xml before editing.


osdinjection.xml holds the “recipe” for boot images and needs to be supplemented with information about the new files.

Open osdinjection.xml in notepad or similar.

As we know there’s already a native file with similar name (tsenv.exe) we will search for that and copy the section, thus avoiding misspelling.

First hit when searching should give you this:


Copy (duplicate) the section and replace the file name:


The result should look like this:

Repeat for x64 (second hit when searching for tsenv.exe):

Save and close osdinjection.xml. Next time a boot image is updated on distribution points TSEnv2.exe will be included.

5         Bootable media Package

As stated earlier we will apply bootable media to disk by script, therefor we will need to create a package containing the necessary files. Use the same procedure as when creating bootable media for use on a USB boot stick, then mount the iso-file and copy the entire content to a new folder on your package share.

Remark – you cannot reuse an old iso; it has to be “fresh” with TSEnv2.exe included.

Make sure to also include “copy.cmd” from Legacy2Uefi.zip.


Create a package in ConfigMgr from the folder, do not create any program.

6         Task Sequence

At this point boot images should be updated and include TSEnv2.exe. We should also have a new package including the small copy.cmd command file. The rest of the work is done in the TS-editor, let’s start….

6.1       Create a new group

Create a new group, call it “Transform to UEFI”.

In our case we have a few extra conditions but as a minimum you should check that the machine isn’t already configured for UEFI (_SMSTSBootUEFI equals False).

The steps within in the group will be explained over the next couple of pages.

6.2       TS Steps

6.2.1      UEFI Config

This step will have to be adapted to local circumstances. It’s simply an example that shows how to reconfigure a HP Laptop to UEFI mode.

Legacy2Uefi.zip contains a folder with only two files:


ConfigUEFI.ps1 is designed to utilize HP’s Bios Configuration utility, which is not included. You also need to create your BIOS password file with the HP tool.

uefi.txt contains a minimum of settings to configure UEFI with SecureBoot.

To make this fully operational more files are needed, these files must be added locally. If you’re an administrator with experience in HP computer this is hopefully enough information to get it working, this is a picture of a functional set of files:


As we prefer keeping bios config files on a network share the step looks like this at most of our customers:

Command: powershell.exe -NoProfile -ExecutionPolicy ByPass -File “%BiosShare%\%Model%\BCU\ConfigUEFI.ps1”

If your running Dell, Lenovo or any other brand – modify as needed. If you don’t have Powershell included in your boot images the script is useless and has to be replaced.

6.2.2      Partition Disk 0 – UEFI Simple

Use a standard “Format and Partition Disk” step to create a GPT disk with a minimal UEFI-compatible partition. The automatically assigned drive letter will be stored in “OSDisk”.

6.2.3      Copy Boot Media to Disk

This is a straight forward “Run Command Line” step that uses the media package and “copy.cmd” to copy the media (iso) content onto the new partition.

”OSDisk” contains the drive letter and tells copy.cmd where to put the content.

Command: copy.cmd %OSDisk%

6.2.4      SET _SMSTSServiceStartType=auto

Another “Run Command Line” step; that invokes TSEnv2.exe and sets ”_SMSTSServiceStartType” to ”auto”.

Command: TSEnv2.exe set _SMSTSServiceStartType=auto

6.2.5      Restart Computer

Next we restart the computer using a standard “Restart Computer” step. Because of the previous modification of the read-only TS-variable we will now be allowed to reboot to the currently installed default operating system, e.g. our media (iso).


6.2.6      SET _SMSTSBootUEFI=true

Finally, we need to modify a second read-only TS-variable. When the TS started the computer was running “Legacy BIOS” and “_SMSTSBootUEFI” was set to “false”.

We need to correct that, as we are now running in UEFI mode.

Command: TSEnv2.exe set _SMSTSBootUEFI=true

7         Done

The rest of the Task Sequence will after the reboot execute as UEFI, no PXE boot needed totally unattended, except for Lenovo Thinkcentre machines but that is a different topic.


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