Cannot start website because of <handlers> in web.config - asp.net-core

Question

I have taken over the development of a software product that we currently deploy on an IIS server. Initially it was running with ASP.net core 2.0 but since I would like to use EF, I have configured the software to use 2.1.
The problem is, when I deploy a new version of our software, I cannot run it successfully. I tried to track down the error and i recognized that the web.config of the successfully running version and the new published version differ from each other.
Here's the version that runs just fine:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.webServer>
<aspNetCore processPath="dotnet" arguments=".\myProject.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" />
</system.webServer>
</configuration>
<!--ProjectGuid: 2b991c10-ec9f-493d-97b9-ee1f96458510-->
And this does not work:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.webServer>
<handlers>
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
</handlers>
<aspNetCore processPath="dotnet" arguments=".\myProject.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" />
</system.webServer>
</configuration>
<!--ProjectGuid: 2b991c10-ec9f-493d-97b9-ee1f96458510-->
Obviously, it's just the handler that makes the difference. When I manually remove it, the software runs fine. How can i make sure that in future publishing processes via VB 2019, this handler is not added to the web.config? Is there any setting that I can make to prevent this error?

Answer 1

For ignoring the web.config during publishing, you could try <IsTransformWebConfigDisabled>true</IsTransformWebConfigDisabled> in *.csproj like
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>netcoreapp2.2</TargetFramework>
<AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
</PropertyGroup>
<PropertyGroup>
<IsTransformWebConfigDisabled>true</IsTransformWebConfigDisabled>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.App" />
<PackageReference Include="Microsoft.AspNetCore.Razor.Design" Version="2.2.0" PrivateAssets="All" />
</ItemGroup>
</Project>
For more information, you could refer web.config file

Answer 2

Unfortunately I cannot reconstruct that initial error message but I solved the problem in the meantime.
The problem was a <handler> tag that was added to the web.config during the publishing. We use a nested website structure with one main website and 4 sub-sites. In this configuration, the handler in the web.config must be removed according to documentation from Microsoft. My former colleague wrote a small xdt-transform script a while ago that was supposed to remove the tag when publishing the software. It always worked fine but it stopped working when I updated the SDK to 2.1. So the handler-tag was added to the web.config and that's why I could not access the website in the first place.
<?xml version="1.0" encoding="utf-8"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document->Transform">
<system.webServer>
<handlers xdt:Transform="Remove" />
</system.webServer>
</configuration>
I figured out that the generated web.config had an additional <language>-tag before the <system.webServer>-tag. Adding the language-tag to the remove script made the script work again. Now that problem was solved and I could at least connect to the website.
But after connecting I received a HTTP Error 502.5. This was due to an old 2.0.7 version of the runtime that was installed on the server. After updating to 2.2 the website finally was rendered correctly.