Is there a way I can share the 3.42 GB download of Windows 8.1 from Windows Store?

I did the update earlier today though and it seems that there is a folder C:\$Windows.~BT that got created and downloaded. You might TRY to take and copy that folder to another 8 machine and see if running the setup file will work for you. If it does...awesome...

However if that doesn't work, Unless it changes later, currently you can get to 8.1 via 3 methods:

1. You can update each machine running 8 via the Windows Store
2. You can use a VL download or Technet/MSDN download. You'll have to have an account though, and I'm pretty sure it won't update non VL 8 machines.
3. You can buy a retail copy on Amazon or similar.

According to the MS Blog on 8.1 they aren't planning an ISO / IT Pro standalone installer:

http://blogs.windows.com/windows/b/bloggingwindows/archive/2013/10/17/windows-8-1-now-available.aspx

We're not releasing the ISO images to folks who don't have MSDN and TechNet subscriptions. Best way for everyone else is to update through the Windows Store. - Brandon LeBlanc (MSFT)

Here are the direct Windows Store ESD (encrypted ISO) links from official website (EN-UK version):

• Windows 8.1 x86

• Windows 8.1 x64

• Windows 8.1 Pro x86

• Windows 8.1 Pro x64

Check out \Windows\SoftwareDistribution\Downloads. There may be some folders with UUIDs for names. Look for one with a date or size that sounds like the update.

In there is WindowsStoreSetupBox.exe with an ESD file. In my case (Windows Pro WMC) 9600.16415.winblue_refresh.130928-2229_x64fre_client_Professionalwmc_gdr_en-us-IR1_CPWMCA_X64FRER_EN-US_ESD.esd. I don't think the store is utilizing the ISO.

If you get prompted to proceed or quit with the inescapable ribbon (example below), and click close, these files get deleted.

I succeeded in installing Windows 8.1 without downloading it again. Here is how I solved it. Before you start, be sure to clear/delete the $Windows.~BT folder.

Then go to \Windows\SoftwareDistribution\Downloads and locate the folder that contains the WindowsStoreSetupBox.exe file and the *.esd file. Copy it to a different location (create a folder).

Then launch an elevated command prompt and go to the location where you copied the .esd file and the WindowsStoreSetupBox.exe.

Enter this carefully and exactly:

WindowsStoreSetupBox.exe /ClassId bd02c22b-1edf-476f-ab78-a72bdada6a47 /SessionId 1 /ReportId {3AB7C5F3-D1B0-4899-8FDD-565910F4D2F7}.1

It should now work a bit and create the $Windows.~BT again and it contains now a Sources folder. Go there and you will find install.esd and setuphost.exe. Launch the latter as administrator.

If everything is fine, a Windows 8.1 window will open. Follow the instructions, and you're good to go.