DotNet Core Setup Failed
Another Solution is to:
- go to the folder where you have downloaded the installer
- open the command prompt by Shift+right click -> Open command window here
- Type -
dotnetcore.1.0.0-vs2015tools.preview2 SKIP_VSU_CHECK=1and hit enter
This should skip the VS update check and start the installation normally.
After applying the other answers here the install was still failing for me. Periodically during the install, a pop-up warning dialog would open stating "The account already exists". I reviewed the Programs and Features list and saw 3 different entries for the VS2015Tools preview. I right-click Uninstall'ed each of them (which removed each one almost immediately), and tried the install again. This time it completed without errors.