I'm not sure if you happened to see the post in the Desktop forum where the following procedure was outlined. However, it did indeed work for others and worked perfectly on both of my XPS 8700s.

Thank you SO much for this tip!

It fixed it! The update appeared and was installed.

I am really flabberghasted that Dell doesn't put that on their 8.1 upgrade checklist

Thanks again!

I see the Windows 8.1 Pro update available in Windows Store, but it never fully downloads.  For the past 2 weeks I've tried to download it.  It gets to ~ 45% complete, then stops and starts over.  I've rebooted the pc many times.  Anyone with same frustrations?

Thanks so much. I spent 4 days trying to update to Windows 8.1 before I found your tip.

No I can finally see it n the Windows store!

At the moment I think you would be better off not upgrading--SERIOUSLY.

If anything goes wrong in the future and you need to repair your system you are asked for your installation or recovery media AND YOU DO NOT HAVE IT FOR 8.1!!!!

You will have to do a reinstall of Windows 8 then update to Win 8.1 then a total reinstall of all software and settings, which is one hell of a task. I have now got to this point on my second (2nd) reinstall.

Microsoft can not help you because the Dell has differences to the retail OS such as the way the OS is activated and Microsoft can not do this. Microsoft Customer Services spent 4 hours trying and admitted failure.

You may also find many of you drivers are unsuitable, look for them on Dell if you have any problems. If you want more info on the OEM problems then just reply to this.

One piece of advice, make sure all your Data is on another partition and backedup.

hello John;  ok, good advice.  Yes, please send  more info on the OEM problems

Hi,

                Rather than repeat myself all over the place the following will give you an initial idea of why I say DON'T Do It.

http://en.community.dell.com/support-forums/software-os/f/4677/p/19528889/20491555.aspx#20491555

http://answers.microsoft.com/en-us/windows/forum/windows8_1-hardware/amd-graphics-driver-not-working-after-installing/9d28d642-ebae-4723-b9f9-e2f703e8f710 and linked articles.

My original 8.1 upgrade failed in the closing stages with no way to restore anything so it was a total reinstall, my second install seemed OK but after a couple of weeks it took 4 to 5 minutes to shutdown so I ran sfc which found corrupt system files which it was unable to repair, my restore points keep disappearing, refresh or reset your PC requires the 8.1 installation media, only available for a retail version of 8.1. I used Windows 8 32 bit when it first came out and the early trial versions which I expected trouble with and got 8 Pro on special offer, which ran fairly well, but I then upgraded my PC and it came with Dell 64 bit Win 8 which again worked quite well for an early incarnation but 8.1 is a can of worms in the way it was implemented and then for some reason the drivers that were fine in 8 either played up or failed in many instance. That is why I say be sure to use Dell supplied drivers some supplied as part of the upgrade are duff on a Dell. Because Ms expect problems the Customer Service Advisers took control of my machine and worked on it for over 4 hours for free and admitted defeat because of the differences in a Dell OS image and Product Key implementation.

I have now install Win 8 in dual boot mode so I have a workable PC whenever the flakiness of 8.1 causes problems, admittedly not with the full range of software I use: The amount of software is why I keep struggling with 8.1but my Wacom Pen and Touch keeps losing it settings and drivers or just gets disconnect for no reason, Windows Fax and Scan fails to work after a short period ( I use an external Fax Modem) and seems do it differently each time. AMD Radeon Catalyst fails and the latest update for mine via Microsoft Updates crashes my laptop. I now kick myself for re upgrading to Win 8.1 after the first failure. They always used to say never opt for a new OS until after Service Pack 1.

Have a good look at the Windows 8.1 Answers site to get an idea of the problems and then decide. Until the way to fix Win 8.1 problems is truly sorted for OEM users it’s a bit like Russian Roulette, pull the trigger enough times and! But in this instance, use the OS enough.

I like the changes made in 8.1, just hate our situation when problems occur.

Microsoft have made Windows 8.0 keys incompatible with Windows 8.1 media during installation. Microsoft have also made Windows 8.0/8.1 product keys hidden within the system BIOS. Finally there is no official means to download Windows 8.1 as a standalone update or as an .iso for an OEM license.

There are however workarounds:

The most difficult part is obtaining the installation media. You can get this if you or a friend have an additional Windows 8.1 retail license by following the instructions here:

http://dellwindowsreinstallationguide.com/download-microsoft-windows-and-office/download-microsoft-windows/download-windows-8-1-iso/

If you don't have a retail key then your only other choice is to look for installation media in unofficial sources as any media procured from Dell will be Windows 8.0 due to Microsoft making Windows 8.0 keys rejected when used with Windows 8.1 media.

Assuming you get the installation media you can install using a generic product key:

http://dellwindowsreinstallationguide.com/a-clean-install-of-windows/microsoft-product-activation/installation-of-windows-8-1-with-a-windows-8-0-retail-product-key-notes/

Next you will need to obtain your BIOS embedded Windows 8.0 product key:

http://dellwindowsreinstallationguide.com/a-clean-install-of-windows/microsoft-product-activation/obtaining-your-oem-bios-embedded-slp-product-key-using-rw-everything-oem-only/

Finally you can activate Windows 8.1 using the Window s8.0 key via the change key:

http://dellwindowsreinstallationguide.com/a-clean-install-of-windows/microsoft-product-activation/product-activation-using-a-windows-8-1-product-key/