ITravelLogStg::TravelTo fails with error 0x80004002

Question

I have these two methods to get the current travel log entry and to travel to a log entry retrieved by calling the GetTravelLogEntry method:

    public static ITravelLogEntry GetTravelLogEntry(WebBrowser webBrowser)
    {
        int HRESULT_OK = 0;

        SHDocVw.IWebBrowser2 axWebBrowser = (SHDocVw.IWebBrowser2)webBrowser.ActiveXInstance;
        IServiceProvider psp = axWebBrowser as IServiceProvider;
        if (psp == null) throw new Exception("Could not get IServiceProvider.");

        IntPtr oret = IntPtr.Zero;            
        int hr = psp.QueryService(ref SID_STravelLogCursor, ref IID_ITravelLogStg, out oret);            
        if ((oret == IntPtr.Zero) || (hr != HRESULT_OK)) throw new Exception("Failed to query service.");

        ITravelLogStg tlstg = Marshal.GetObjectForIUnknown(oret) as ITravelLogStg;
        if (null == tlstg) throw new Exception("Failed to get ITravelLogStg");            
        ITravelLogEntry ptle = null;
        hr = tlstg.GetRelativeEntry(0, out ptle);
        if (hr != HRESULT_OK) MessageBox.Show("Failed to get travel log entry with error " + hr.ToString("X"));
        Marshal.ReleaseComObject(tlstg);
        return ptle;
    }

    public static void TravelToTravelLogEntry(WebBrowser webBrowser, ITravelLogEntry travelLogEntry)
    {
        int HRESULT_OK = 0;

        SHDocVw.IWebBrowser2 axWebBrowser = (SHDocVw.IWebBrowser2)webBrowser.ActiveXInstance;
        IServiceProvider psp = axWebBrowser as IServiceProvider;
        if (psp == null) throw new Exception("Could not get IServiceProvider.");

        IntPtr oret = IntPtr.Zero;
        int hr = psp.QueryService(ref SID_STravelLogCursor, ref IID_ITravelLogStg, out oret);
        if ((oret == IntPtr.Zero) || (hr != HRESULT_OK)) throw new Exception("Failed to query service.");

        ITravelLogStg tlstg = Marshal.GetObjectForIUnknown(oret) as ITravelLogStg;
        if (null == tlstg) throw new Exception("Failed to get ITravelLogStg");            
        hr = tlstg.TravelTo(travelLogEntry);
        if (hr != HRESULT_OK) MessageBox.Show("Failed to travel to log entry with error " + hr.ToString("X"));
        Marshal.ReleaseComObject(tlstg);
    }

The WebBrowser here is a .NET WebBrowser control. When calling ITravelLogStg::TravelTo inside the TravelToTravelLogEntry method I'm getting a 0x80004002, which according to this page is a Interface not supported error. Am I doing something wrong?

PD: I took most of this code from here.

Answer 1

Well you are trying to navigate to the current entry in the travel log which doesn't make much sense as you are already there. I could reproduce the error for this specific case and find it not very helpful, too.

But using anything else then 0 as first parameter for GetRelativeEntry and then calling TravelTo worked as expected.

ITravelLogStg::GetRelativeEntry returns the entry specified by the offset. A positive offset returns an entry after the current entry; a negative offset returns an entry before the current entry. Zero returns the current entry.

(Source: MSDN)

Try modifying hr = tlstg.GetRelativeEntry(0, out ptle); - the first parameter specifies in which direction you want to navigate. Using other values than 0 should work, e.g. you could use -1 to travel one entry backward.