Windows 10 Pro upgrade missing "boot.wim" file

Question

I am trying to install/upgrade Windows Pro 8.1 to Windows 10 through setup.exe from C:\$Windows.~BT. But installer tell me that boot.wim file is missing.

In update history logs I can see that update to windows 10 failed many times since july 29th.

Answer 1

I had the exact same error while I wanted to upgrade from Windows 8.1 to Windows 10. My solution was the following:

1. Log in as an administrator.
2. Press Windows+R, enter regedit and press enter to open the registry editor.
3. Locate the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\OSUpgrade (if it's missing, create it)
4. Create a new DWORD (32-bit) value, call it AllowOSUpgrade and set its value to 0x00000001.
5. Restart the control panel, browse to "Windows Update" and search for updates (if the button from step 6 is not already there).
6. Now, a button with Getting started should appear. Click on it and follow the instructions to install Windows 10.

Source: http://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/windows-update-installation-failure-80240020/d695e827-9774-4e10-8972-df8d51a7bb51