beeradmoore/dlss-swapper · error · Exception

Failed to get result from file open dialog.

Error message

Failed to get result from file open dialog.

What it means

In FileSystemHelper.OpenFileInternal (multi-select path), each item of the ShellItemArray returned by the IFileOpenDialog is fetched with GetItemAt. If any item comes back null the helper cannot produce a path for it and throws this exception. It indicates the Shell gave a result collection containing an unusable entry.

Solutions

1. Treat null items as skippable: continue enumerating remaining items instead of failing the whole operation.
2. GetDisplayName on each item inside try/catch and skip items whose SIGDN_FILESYSPATH cannot be resolved.
3. Validate the selection before closing (filter to filesystem items) if the dialog configuration allows it.
4. Log the index and count when skipping to aid diagnosing shell-provided bad items.

Example fix

// before
ppsiArray.GetItemAt(i, out var ppsi);
if (ppsi is null) throw new Exception("Failed to get result from file open dialog.");
// after
ppsiArray.GetItemAt(i, out var ppsi);
if (ppsi is null) continue; // skip unavailable item instead of failing all selected files

// no pre-call validation possible for shell internals; guard the item after GetItemAt
ppsiArray.GetItemAt(i, out var ppsi);
if (ppsi is null) { skipped++; continue; }

static bool IsUsableShellItem(IShellItem? item) => item is not null;

try
{
    CollectDialogItems(ppsiArray, count, results);
}
catch (Exception ex) when (ex.Message == "Failed to get result from file open dialog.")
{
    // return whatever paths were collected so far instead of failing all
}

When it happens

Trigger: During enumeration of a multi-file selection, ppsiArray.GetItemAt(i, out ppsi) succeeds but yields a null IShellItem at index i — e.g. an item that was removed or became unavailable between selection and retrieval (network share/removed device), or a shell namespace item without a filesystem representation.

Common situations: User selects files on a network drive or removable media that disconnects before the dialog result is processed; virtual shell items (This PC, libraries) surfaced into the result; Windows shell edge cases with unusual file pickers.

AI-assisted analysis of beeradmoore/dlss-swapper@ab9b1e2d4b (2026-09-15). Data as JSON: /api/errors/dd4fe3b7306729a9. Report an issue: GitHub.

Appendix: source

Thrown at src/Helpers/FileSystemHelper.cs:187

            fileOpenDialog.Show(new HWND(hWnd));

            var results = new List<string>();

            if (pickMultiple)
            {
                fileOpenDialog.GetResults(out var ppsiArray);

                unsafe
                {
                    ppsiArray.GetCount(out uint count);
                    for (uint i = 0; i < count; ++i)
                    {
                        ppsiArray.GetItemAt(i, out var ppsi);

                        if (ppsi is null)
                        {
                            throw new Exception("Failed to get result from file open dialog.");
                        }

                        PWSTR filename;
                        ppsi.GetDisplayName(SIGDN.SIGDN_FILESYSPATH, &filename);
                        var pathName = filename.ToString();
                        results.Add(pathName);
                    }
                }
            }
            else
            {
                fileOpenDialog.GetResult(out var ppsi);

                if (ppsi is null)
                {
                    throw new Exception("Failed to get result from file open dialog.");
                }

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