It’s easy to reproduce this problem using a simple html fragment (save as test.html):

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Asked: May 29, 20262026-05-29T19:15:47+00:00 2026-05-29T19:15:47+00:00

It’s easy to reproduce this problem using a simple html fragment (save as test.html):

0

It’s easy to reproduce this problem using a simple html fragment (save as test.html):

<style>
    a { behavior: url(#default#AnchorClick); }
</style>
<a href="https://webdav.mc.gmx.net/" folder="https://webdav.mc.gmx.net/" target="_blank">open</a>

If you open test.html in InternetExplorer and click on the open link, a new windows explorer pops up with the specified WebDAV folder. This is exactly what I expect.

Now if I open test.html inside the WPF WebBrowser-Control, the behavior is different. It opens a new Internet Explorer Window, showing a HTTP 405 error.

Here is the XAML and Code-Behind to test it in WPF WebBrowser:

<Window x:Class="Misc.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <WebBrowser x:Name="_browser" />

using System.IO;

namespace Misc
{
    public partial class MainWindow
    {
        public MainWindow()
        {
            InitializeComponent();
            var folder = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
            var file = Path.Combine(folder, "test.html");
            _browser.Navigate(file);
        }
    }
}

NOTE:

In both cases, because it is a local file, you need to “Allow Blocked Content” first (yellow bar at top).
The URL in this sample isn’t the real one, because it is accessible on the intranet only. The real URL points at a SharePoint WebDAV Folder.