There has been a lot of misinformation in the Insider’s Forum (from customers) about the necessary free space to install an Insider’s Build. I decided to take my only low memory device, an ASUS Vivo Tab 8 M81C-B1-MSBK Signature Edition Tablet that I purchased from the Microsoft Store, and test this out for myself. The device is 32GB to start with and was VERY full. A little over 4GB free space was available. Nevertheless, I was able to install an Insiders Build from a mounted ISO and subsequently download and install the latest Fast Ring Insider’s Build from Windows Update.
Here’s how I did all of this:
I used the following procedure to install 14372 from an ISO image. This is the process that should work for folks upgrading from 10586.xxx 1511 to the official release of the Windows Anniversary Update (with a few changes on where and how to get the ISO) with minimal free space.
The first problem is that the default Downloads folder was on C:\ and only a bit over 4GB of free space was available, so I needed to move Downloads to my 128GB microSD card. I wanted to move this at the System level as opposed to just specifying a different folder. The ISO for 32 bit Windows is 3GB+ and to say the least, with only 4+ free, I needed to download to a drive other than C:\.
The process to move the folder is to right click/tap and hold the Downloads Folder and then select Properties, then the Location tab.
Then, select the Move button.
Then, navigate to the alternate or external storage you want to use (in my case it was my 128GB microSD card) and select Apply. A windows will display asking you to confirm the move and ask whether you want to move existing content (which is what you should do). Again, I specified the root drive, but you can easily create a folder and specify it as instead.
Once the default Download folder was moved off the C:\ drive, the next step was to download the 14372 ISO and then mount it. After I ran setup.exe, a message displayed stating more space was needed. Use Disk Cleanup is the default choice, but I selected “Choose another drive or attach an external drive…”
I already had a microSD card with 70+GB free so I used the drop down to select that drive.
Once the D:\ drive was selected, I selected Refresh and the installation continued.
Windows Insider Build 14372 proceeded to install without any issues. Once I had the desktop up, I checked a few things and then opened Disk Cleanup (easily discoverable using Search/Cortana) and used the Advanced button which after a few minutes displayed everything I could delete on the main C:\ drive. I proceeded by selecting “Previous Windows Installations” and acknowledged all prompts.
The Disk Cleanup process gave me a whopping 6GB free.
Next, I opened Settings, Updates and Security, and since this tablet was configured for the Fast Ring, lo and behold, 14385 was offered. And it downloaded and installed beautifully.
Update: I just installed 14388 following basically the same process (run disk cleanup and remove previous Windows installations, insure that the Downloads location is moved to a drive other than C:\ and then install from Windows Update).
This system worked for me and I hope this is helpful. You can reach me on Twitter @barbbowman or in the Microsoft Windows/Windows Insider Forums.