No bootable devices found (XPS 15 9550)

Hi Hk417a,

Thanks a lot for descibing the steps which delivered the solution for me.

Afterwards, I could enter Windows again. Thanks a lot for your help in this. Really appreciated!

KR, René

How did you get to this software option?

Perfect - saved my life!

Hi, I tried the same with the new BIOS Update (1.2.29), no luck. Any suggestions?

Unplug the dock, if you're using one, and use a regular AC adapter instead. 1.2.29 makes dock USB go berserk again.

You Save my life! thanks! it works for me! after hours of looking how to solve!

So if I understand this correctly, affected users found their systems set to Legacy rather than UEFI?  If so, fyi just setting it back to UEFI should have resolved the issue without the need to manually add a boot entry since the UEFI spec mandates that systems check any detected devices for a bootx64.efi file at that \EFI\Boot path automatically.

But either way, Dell BIOS updates in addition to making USB devices attached via the TB16/WD15 docks practically unusable are now also modifying boot settings and rendering disks unbootable without making these changes to restore functionality?

Windows 7's files were never set up to boot as UEFI because it could never boot in true UEFI mode anyway.  It can only boot in UEFI mode when Legacy Option ROMs/CSM is enabled. Normally that of course means that it is in fact booting in Legacy mode, but it's not.  It can be installed to and booted from a GPT disk and it will show up as a UEFI option, but it will blue-screen when trying to boot unless Legacy Option ROMs is enabled -- so I guess its kernel has some sort of dependency on that even when booting in UEFI mode.  Anyhow, Windows 8 and up place their bootx64.efi file in the path that the UEFI spec says must be checked automatically. For anything else, yes you would have to manually add a boot entry.

I suppose it's possible that a Windows update inappropriately modified the BCD store, but in that case the fix would ALSO have involved modifying the BCD store, not making BIOS configuration changes.  Additionally, some users have reported this issue SOLELY as a result of updating their BIOS, without any Windows updates in the mix. I don't think seeing someone's BCD store would provide any insight into this particular issue since that only comes into play once the bootx64.efi file is loaded to begin with.

I remember, back in the day of Win 7, because Microsoft was not setting up things like recovery drives to boot as UEFI, that we had to add a special folder for that purpose.  The folder was Boot and we renamed the bootmgfw.efi file to bootx64.efi.  

Since the normal boot files point to EFI\Microsoft\boot\bootmgfw.efi, what is happening to that normal process?  I have always felt some update had modified the boot files to install an update and could not return them to normal.  But since none of my systems have ever run into this situation, I cannot check for myself.

It would be really nice if someone who had gotten their system boot after this problem, would open an administrative command prompt and type bcdedit or bcdedit /enum all and either copy and paste the first part or make the file avialable in a zip format somehow.  I do not know if you can attach files in this forum.

In my experience, I have not seen a system change the default settings in the Bios from UEFI to Legacy.  I am not saying, however, it cannot happen under some unusual circumstance.

How Win 7 boots/Bioses has evolved over time but UEFI is UEFI, secure Boot was not involved. 

But that is not relevant to my statement.  I would be nice to pin down why these systems were loosing their boot device.  There is always a chance, someone who has actually had the problem, can find the cause.

Windows 7 did not change its boot mechanism over its lifetime.  It has the same level of UEFI support now as it did when it first launched -- and I didn't say anything about Secure Boot.  Win7 does not support Secure Boot, but simply disabling that WITHOUT also enabling Legacy Option ROMs/CSM will not allow it to boot in UEFI mode.  I agree it isn't relevant to this discussion, but you're the one who brought it up. :)

And yes, it would indeed be nice to know precisely what these users found in their BIOS before they implemented the fix described here, which is why I asked.

I just had this problem following upgrade to Bios V1.3. These instructions fixed it for me. Please get someone at Dell to urgently check the V1.3 BIOS update in case it causes problems for other people.

On Point 6 it should say "tick" not "ticket". I unticked the other two options so only "My Boot" was ticked. Is that step important? If so it might be worth adding to your post.

Thanks!

Andrew