ASP.NET Core with IIS - HTTP Verb Not Allowed

This was what worked for me (netcore 2.0)

<system.webServer>
  <modules runAllManagedModulesForAllRequests="false">
    <remove name="WebDAVModule" />
  </modules>
</system.webServer>

Found here: https://www.ryadel.com/en/error-405-methods-not-allowed-asp-net-core-put-delete-requests/

Whilst removing WebDAV may solve your issue, you may be wondering (like I was), what is WebDAV and what is it used for?

I found this page which helps explain it:

https://www.cloudwards.net/what-is-webdav/

After hours of research and trial and error, the fix seems to be pretty simple. Add a Web.config file to your .NET Core 2.0 application:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <!-- To customize the asp.net core module uncomment and edit the following section. 
         For more info see https://go.microsoft.com/fwlink/?linkid=838655 -->
    <system.webServer>
        <modules>
            <remove name="WebDAVModule" />
        </modules>
        <handlers>
            <remove name="aspNetCore" />
            <remove name="WebDAV" />
            <!-- I removed the following handlers too, but these
                 can probably be ignored for most installations -->
            <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
            <remove name="OPTIONSVerbHandler" />
            <remove name="TRACEVerbHandler" />

            <add name="aspNetCore" 
                 path="*" 
                 verb="*" 
                 modules="AspNetCoreModule" 
                 resourceType="Unspecified" />
        </handlers>
        <aspNetCore processPath="%LAUNCHER_PATH%" 
                    arguments="%LAUNCHER_ARGS%" 
                    stdoutLogEnabled="false"
                    stdoutLogFile=".\logs\stdout" />
    </system.webServer>
</configuration>

Hope this helps.