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/