@Sparkash - as I recall 80860003 was caused by a mismatch between service and client side configuration of the application. I suspect this is not a Creators Program title? In which case make sure to leave that box unchecked in the Project Settings. Also make sure that your build is turning out an AppxManifest.xml with Package/Identity/Name and Package/Identity/Publisher values that exactly match Dev Center. If you have the latest version of the code then there are now dedicated fields for these in the UWP Project Settings page (Packaging section, Advanced display); if not specified, or on older versions of the source, these come from the Project Name and Company Distinguished Name in general project settings.
XDK title issues are best dealt with through private support channels.
@anonymous_user_1267f45c - the 2015 suffix shouldn’t be a problem. It’s just indicating that the projects are in 2015 format. For UE projects this is independent of which toolset is used when building. If you want to switch everything to 2017 format and toolset you can re-run GenerateProjectFiles with -2017 on the command line.