Today is the day that Windows 10 started to roll out globally. For those of you that have been lucky enough to get the first batch of installs you may experience an error with the download 80240020. If you do then follow the instructions below.
Error Code 80240020
What this error means is, your Windows 10 installation folder is unfinished and/or corrupted. Now, how do you fix that?
1. Go into “C:\Windows\SoftwareDistribution\Download” and delete everything in that folder.
2. Now, run the command prompt as an administrator. Type in “wuauclt.exe /updatenow”.
3. Go to your Control Panel > Windows Update and your Windows 10 should start re-downloading from scratch, hopefully without flaws this time.
…the above is thanks to Losemind.