iOfficeAI/OfficeCLI · error · InvalidOperationException

word_not_authentic: {name}

Error message

word_not_authentic: {name}

What it means

Thrown by DocxToPdf after CoCreateInstance instantiates CLSID {000209FF-0000-0000-C000-000000000046} (Word.Application) and queries its Name property. If the name does not contain 'Microsoft Word' (case-insensitive), the backend refuses to proceed, because a different application or a non-Word COM server registered under that CLSID would silently produce garbage or hang. This is a security/authenticity guard: it prevents the PDF backend from driving an unexpected or spoofed COM server that happens to occupy Word's class ID.

Source

Thrown at src/officecli/Core/WordPdfBackend.cs:461

                int srcStride = p.w * 4;
                for (int row = 0; row < p.h; row++)
                    Array.Copy(p.pixels, row * srcStride, target, (y0 + row) * targetStride + x0 * 4, srcStride);
            }
            return EncodeBgraToPng(factory, target, W, H);
        }
        finally { Marshal.Release(factory); }
    }

    static string DocxToPdf(string docx)
    {
        var pdf = Path.Combine(Path.GetTempPath(), $"_w_{Guid.NewGuid():N}.pdf");
        var clsid = G_Word; var iid = G_IDispatch;
        CoCreateInstance(ref clsid, IntPtr.Zero, 4, ref iid, out var word);
        try
        {
            var name = (string?)DispGet(word, "Name") ?? "";
            if (!name.Contains("Microsoft Word", StringComparison.OrdinalIgnoreCase))
                throw new InvalidOperationException("word_not_authentic: " + name);

            DispSet(word, "Visible", false);
            DispSet(word, "DisplayAlerts", 0);
            try { DispSet(word, "AutomationSecurity", 3); } catch { }

            var docs = (IntPtr)DispGet(word, "Documents")!;
            try
            {
                var doc = (IntPtr)DispMethod(docs, "Open", docx, MISSING, true, false)!;
                try { DispMethod(doc, "SaveAs2", pdf, 17); }
                finally { try { DispMethod(doc, "Close", false); } catch { } Marshal.Release(doc); }
            }
            finally { Marshal.Release(docs); }
        }
        finally
        {
            try { DispMethod(word, "Quit"); } catch { }
            Marshal.Release(word);

View on GitHub (pinned to 1ced45e900)

Solutions

1. Run 'winword.exe' manually to confirm Word launches and reports itself as 'Microsoft Word' in its title bar.
2. Repair the Office installation: Settings > Apps > Microsoft 365/Office > Modify > Online Repair.
3. If the Name property returns a localized or version-specific string (e.g. 'Microsoft Word 2016'), the Contains check already handles that — if it still fails, inspect the exact Name value returned and report it.
4. On a server, install Word via a volume-license Office build rather than click-to-run, which is known to leave registration stubs.

// Check that Word reports itself correctly before relying on the backend
// This mirrors the internal check; if it fails, PDF conversion is unavailable
var clsid = new Guid("000209FF-0000-0000-C000-000000000046");
var iid = new Guid("00020400-0000-0000-C000-000000000046");
try
{
    WordPdfBackend.CoCreateInstance(ref clsid, IntPtr.Zero, 4, ref iid, out var word);
    try
    {
        var name = (string)WordPdfBackend.DispGet(word, "Name");
        if (!name.Contains("Microsoft Word", StringComparison.OrdinalIgnoreCase))
            throw new PlatformNotSupportedException($"Word authenticity check failed: {name}");
    }
    finally { Marshal.Release(word); }
}
catch { /* Word not available or not authentic */ }

try
{
    var pdf = WordPdfBackend.DocxToPdf(docxPath);
}
catch (InvalidOperationException ex) when (ex.Message.StartsWith("word_not_authentic"))
{
    // The COM server under Word's CLSID is not genuine Microsoft Word
    logger.LogError("Word authenticity check failed: {Detail}", ex.Message);
    throw new PlatformNotSupportedException(
        "PDF conversion requires genuine Microsoft Word to be installed.");
}

When it happens

Trigger: The CLSID {000209FF-...} is registered but resolves to something other than Microsoft Word — e.g. an Outlook MAPI or Office runtime stub on machines with only a partial Office install, a third-party application that hijacked the CLSID, a Wine/Corosiva-CrossOver environment where the COM server reports a different Name, or a registry corruption where Word is partially uninstalled but the CLSID entry remains.

Common situations: Server with Office Online Server or Office runtime redistributable but no desktop Word; a machine with only Microsoft 365 click-to-run streaming stub where Word is not fully downloaded yet; WINE/CrossOver where the COM bridge reports a Wine-specific name; a damaged Office install after a failed update.

Related errors

• Invoke({name}) hr=0x{hr:X8}

AI-assisted analysis of iOfficeAI/OfficeCLI@1ced45e900 (2026-08-13). Data as JSON: /api/errors/8b0eec1af96f9b30. Report an issue: GitHub.