Windows 10 Upgrade tool fails 0x8007001F-0x30000D

I ran into the error code 0x8007001F-0x30000D when trying to update from Windows 7 to Windows 10.
Many articles on the web point out, that the problem occured due to moving the /Users folder to another drive.
When installing Windowns 7 I set up my /Users on another hard drive (E:\). My hard drive mounted on E: has a capacity of 2 TB, while my C: drive has 256 GB. My /Users folder has used up 542 GB, so moving back to C:/ and performing the update won't work.
Is there another option to make the update work?