

CAUSE : Systems that have 32GB eMMC disk space may be notified that there is insufficient space while installing large Windows updates or upgrading to Windows 10.
SOLUTION: Connect a USB flash drive, external hard drive, or SD card with enough free space to install the update. The drive you connect must be 8 GB or larger (16 GB is recommended). You will need to keep this drive available if you want to use the go back feature in Windows 10 to return to your original operating system.
Note: Some models like the Aspire R3-131T and ES1-111m do not support using an SD card to install the update. You will need to use a USB flash drive when installing the Windows 10 update on these models.
SOURCE: https://us.answers.acer.com/app/answers/detail/a_id/38036When there is no enough space for Windows update, the first thing that you can try is to delete useless files to free up more space. However, it’s far from enough. If you have applications installed in your computer but never used or hardly used, uninstall them from your Control Panel.
Go to Settings > System > Storage, scroll down and click Temporary files in the right panel. Then you will see a list of files you can remove. Then check the boxes next to the files that you intend to delete and then click the button of Remove files to clean these files.
Open Disk Cleanup in your computer, select C drive as the target drive that you want to clean up and click OK. Under Files to delete, scroll down and choose useless and unnecessary files, and then click the button of OK to go on. Click Delete Files to confirm.
You can rely on a third party tool to clean the C drive when C drive doesn't have enough space for Windows 10 update. iSunshare System Genius is a professional tool for junk file cleanup and system optimization. You can make use of it to clean C drive and free up more space.