Every time I open the launcher I get the following error message :
Error
The necessary prerequisites have failed to install. Error Code R-1603.
I have had problems in the past when installing unreal prerequisites with the Setup.bat that comes with the source version, but this is the first time the Epic Games Launcher gives me this kind of error.
I attach a zip file with the latest logs with Debug Logging enabled and my DXDiag.
Hello TS100101,
I’m sorry to hear that you’re having trouble Your issue appears to be the same as the topic here.
Please make sure you are logged in on an account that has Administrator privileges. You can also try right clicking the Epic launcher shortcut and selecting “Run As Administrator”.
If this does not resolve your issue, please reply back and we will continue to look into the issue for you.
Running the launcher as administrator didn’t solve anything, but I recently upgraded to Windows 10 and I no longer have any issues.
I had this same exact problem so I went into the properties and ran in compatibility with Windows 7 
and when it says your shortcuts are outdated DO NOT UPDATE THEM!!!