Do not try this solution before trying others as the first step just deletes everything in the directory C:\Program Files (x86)\Microsoft Visual Studio\2017\
The only solution which worked for me was:
run C:\Program Files (x86)\Microsoft Visual Studio\Installer\resources\app\layout\InstallCleanup.exe -full
run C:\Program Files (x86)\Microsoft Visual Studio\Installer\vs_installer.exe with admin rights
- click modify and add some option