유틸리티 ESDtoISO tool by Kari - 20150702

Let's try to clarify this. If you are simply looking instructions to see how to make an ISO, do not read further, simply jump to the first page, download the tool and follow the simple instructions.

For those reading further, here's how it works when told quite simplified.

Microsoft uses the so called RSA encryption for it's Electronic Software Distribution (ESD) files. In case of Windows 10 build upgrades, Windows Update downloads the package, unpacks it and finally decrypts the files in it. Not the other way around even if it would seem more logical, the install.esd just unpacked is still encrypted. The ESD file is basically an archive containing the boot.wim, install.wim and other files needed for Windows upgrade and installation., all other files in the package needed for the unpacking and decryption.

Windows 10 build upgrade files are always encrypted when downloaded to your computer through Windows Update.

When you see the download in Settings > Update & Security > Windows Update reaching the full 100%, the next step is to unpack the archive. When this starts you will see the text Preparing to install updates. If you now monitor the C: drive you will see system creating the working folder C:\$Windows.~BT\ and starting to unpack the files from the archive. The file we are interested in, the install.esd file will be unpacked to the subfolder Sources (C:\$Windows.~BT\Sources).

Follow the progress in Settings > Update & Security > Windows Update; when Preparing to install updates reaches about 50%, the unpacking has been done and Windows starts the final phase before the upgrade itself starts and decrypts the files.

Those who just want to upgrade need to do nothing. Just relax and let the system download, unpack and decrypt the files and Windows will upgrade itself. Those like me who do not want to wait an extra hour or so for the upgrade to finish but want the ISO instead as soon as possible have a little bit stress now: the ESD needs to be grabbed and taken to a safe place as soon as it has been unpacked but still encrypted because if we wait until the decryption is done before we start the copy process, the upgrade process will start before the copy process has finished and the file we are currently copying disappears.

I repeat that the above is a "verbally illustrated" and simplified description of the real process but I hope you got it .

Kari

ESDtoISO (Build 10130 and older ESD files).zip

ESDtoISO (Build 10158 and later).zip