Ugh! You've just tried for the 10th time to install Visual Studio 2019, and the installer exits without doing anything and without saying anything useful in the logs. The last thing in dd_bootstrapper_.log is:

   VS setup process starting. Exiting with code 0
   Start named pipe:
   Pipe disconnected.
   Bootstrapper sucessfully completed.

What's happening? Microsoft has it out for you. Well, maybe not [1], but it seems that way. If you're running Windows 7, the problem could be that you don't have the right root certificates. And no, manually installing the ones from the VS layout\certificates folder won't help.

To see whether this is the problem, go to c:\program files (x86)\Microsoft Visual Studio\Installer and double-click vs_installer.exe. If you get a dialog complaining about an invalid certificate for vs_installershell.exe, you're in luck. Download KB 3004394 from MS (https://www.microsoft.com/en-us/download/details.aspx?id=45633 ), check the download's digital signature and certificate chain for validity (you always do that, right?) and install it. Then reboot and retry your VS 2019 install.

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[1] I nominate Microsoft as the entity that has wasted the most person-hours in all of human history.

Comments:

(a) After hours of frustration, I found the guts of the above answer via user "lily332" at https://developercommunity.visualstudio.com/content/problem/676241/vs-installershell-has-an-invalid-certificate-vs.html .

(b) I still do not understand why MS replaced simple, reliable .iso file downloads with the unholy mess that builds their offline installer. The new approach is buggier, slower, more difficult to use, more difficult to diagnose, less secure in that it requires you to give network access to a mess of new programs, and more difficult to control.

Please, MS, bring back .iso downloads. And sign them with GPG while you're at it.