You receive the error message HTTP Error 500.35 - ANCM Multiple In-Process Applications in same Process when Hosting Multiple ASP.NET Core Sub-Sites on a Single Site Hosting Account.
It might be caused by a setting in either the web.config file for the sub-domain or for the main site. If the file has these attributes:
modules="AspNetCoreModuleV2"
hostingModel="InProcess"
Then change them to:
modules="AspNetCoreModule"
hostingModel="OutOfProcess"