I just installed Delphi 10.3 on my workstation (with Delphi XE6 and Delphi 10.1).
I checkout the branch hotfix/1.2.2.
When I launch build.exe I can select Delphi 10.3 Win32, Win64 and Linux64. Debug and/or Release.
But when I click the build button the console window popup and disappear immediately.
There is no file in the Logs folder but I can see a kind of "File not found" (sorry my Windows is in french) error in the console window.
I found BuildHelper.bat call "C:\Windows\Microsoft.NET\Framework\v4.5\msbuild.exe" but I have not installed this version of the framework.
Well that is what the installer reads from the rsvars.bat in your bds\bin directory. If you don't have that framework version then you cannot use msbuild which the installer tries to use. I actually expected the RAD Studio installer to take care of that but whatever.
In a distant future we might write a new installer or get rid of it altogether.
As you can see in buildhelper.bat it calls %FrameworkDir%\msbuild.exe and %FrameworkDir% is set in rsvars.bat to the directory you mentioned in your previous comment.
Make sure your %PATH% did not get too long. It gets truncated then.
I found that my rsvar.bat was OK and I am still not having any success with build.exe. I have also confirmed that .NET is >4.5 (running on Windows 10 April update). I am suspecting it may have something to do with the fact that I still have 10.2.3 installed on C: (SSD) and opted to place 10.3 on my much more spacious (rust) D drive. Build.exe not working is not a show stopper for me. I am able to build everything fine via the 10.3 IDE.
Once other 3rd party dependencies have published updates for 10.3, I will no longer need 10.2.3 and will remove it. I plan to give Build another try at that time.
Build is reporting that it cannot complete the task and lists off 10.3 RIO. I apologize for not being more specific (exact). I am working from memory at the moment and not at the actual computer that has the issue. I am also only trying to build for RIO 32 bit at this point.
If there is anything you would like me to look into, in the meantime, I would be happy to do so.