6.1.9 is not compatible with uap10.0.17763

[AK51]

I try to build the UWP but I got these errors.
Severity Code Description Project File Line Suppression State
Error CS2001 Source file 'D:\…….\UWPSampleCode\obj\x86\Debug\App.g.i.cs' could not be found. UWPSampleCode D:....\UWPSampleCode\CSC 1 Active
Severity Code Description Project File Line Suppression State
Error CS2001 Source file 'D:\….\UWPSampleCode\obj\x86\Debug\Controls\NotifyPopup.g.i.cs' could not be found. UWPSampleCode D:....\UWPSampleCode\CSC 1 Active

[AK51]

I lower the version and I got different error.
Loading assembly "C:\Users\…..nuget\packages\runtime.win10-x86.microsoft.netcore.universalwindowsplatform\6.1.7\runtimes\win10-x86\lib\uap10.0.15138\Microsoft.Win32.Primitives.dll" failed

[queequac]

I do builds with 6.1.9 and Windows 10.0.17763. So this should not be a general issue.
Did you try to "rebuild all"? Seems the files in obj and bin are outdated and don't fit to the target platform.