Installed Windows 10 Home x86 on both Stream 7 and Dell Venue 8 3000. Both these are WIMBOOT devices, upgrading from ISO mounted from C: will be unsuccessful, so extract the ISO to a USB storage drive, then upgrade from there within Windows. Make sure you have fully charged battery, or use one of the OTG cable/peripherals which allow you to charge and use USB at the same time. Don't do a clean install. After it has restarted, you can basically remove the USB and just charge it. The setup will still continue. I left mine overnight as it was already 3AM and both were successful. After upgrade, run Windows Update and download all the latest drivers and errthing because the video will be choppy and laggy after upgrade.
I know it's not a Stream 8, but it's basically an upscaled Stream 7, so if it works in Stream 7 should also work in Stream 8.
If you are still unsuccessful, reset everything first before upgrade. Could be the storage space running low.