iOfficeAI/OfficeCLI · error · NotSupportedException

Unsupported file type: {ext}. Supported: .docx, .xlsx, .pptx

Error message

Unsupported file type: {ext}. Supported: .docx, .xlsx, .pptx, or any extension served by an installed format-handler plugin that implements `create`.

What it means

Thrown by BlankDocCreator.Create when the target path's extension is not .docx/.xlsx/.pptx and no format-handler plugin claimed it via TryCreateViaPlugin. It is a NotSupportedException that surfaces when `officecli create <path>` (or any path that routes to blank-doc creation) is asked to produce a format OfficeCLI has no built-in or plugin writer for.

Source

Thrown at src/officecli/BlankDocCreator.cs:31

public static class BlankDocCreator
{
    public static void Create(string path, string? locale = null, bool minimal = false)
    {
        var ext = Path.GetExtension(path).ToLowerInvariant();
        switch (ext)
        {
            case ".xlsx":
                CreateExcel(path, locale);
                break;
            case ".docx":
                CreateWord(path, locale, minimal);
                break;
            case ".pptx":
                CreatePowerPoint(path, locale);
                break;
            default:
                if (TryCreateViaPlugin(path, ext)) break;
                throw new NotSupportedException($"Unsupported file type: {ext}. Supported: .docx, .xlsx, .pptx, or any extension served by an installed format-handler plugin that implements `create`.");
        }
    }

    /// <summary>
    /// Delegate creation of an unknown extension to a registered format-handler
    /// plugin, if one exists for that extension and exposes a `create &lt;path&gt;`
    /// CLI subcommand. Returns <c>true</c> if a plugin was found and produced
    /// the file successfully. Generic per plugins/plugin-protocol.md — keeps
    /// BlankDocCreator format-agnostic; any plugin that implements the
    /// `create` subcommand on its executable participates.
    /// </summary>
    private static bool TryCreateViaPlugin(string path, string ext)
    {
        var plugin = OfficeCli.Core.Plugins.PluginRegistry.FindFor(
            OfficeCli.Core.Plugins.PluginKind.FormatHandler, ext);
        if (plugin is null) return false;
        var psi = new System.Diagnostics.ProcessStartInfo
        {

View on GitHub (pinned to 1ced45e900)

Solutions

1. Change the target extension to a supported one: .docx, .xlsx, or .pptx.
2. Install a format-handler plugin that implements the `create` subcommand for the desired extension (see plugins/plugin-protocol.md), then retry.
3. Pre-validate the extension in your wrapper script before calling create.

Example fix

# before
officecli create report.pdf

# after
officecli create report.docx

// Validate the extension is supported (or plugin-backed) before calling Create.
static readonly HashSet<string> BuiltIn = new(StringComparer.OrdinalIgnoreCase) { ".docx", ".xlsx", ".pptx" };
var ext = Path.GetExtension(path);
if (!BuiltIn.Contains(ext) && !PluginHandler.IsRegistered(ext))
    throw new InvalidOperationException($"Refusing to create unsupported extension {ext}; use .docx/.xlsx/.pptx");
BlankDocCreator.Create(path, locale);

// Guard: is this extension one Create can handle?
static bool IsCreatable(string path) =>
    Path.GetExtension(path).ToLowerInvariant() is ".docx" or ".xlsx" or ".pptx";
// (add a plugin-registry check for custom extensions)

When it happens

Trigger: `officecli create report.pdf`, `officecli create notes.odt`, `officecli create data.csv`, or `officecli create slide.key` when no plugin registered for that extension. The switch in Create() falls to default, TryCreateViaPlugin returns false (PluginRegistry.FindFor finds nothing), and the throw fires.

Common situations: User assumes `create` works for any Office-adjacent format; a script passes a user-supplied filename without validating the extension first; a plugin that should handle the format is not installed or not on PATH; the extension has different casing/whitespace that bypassed ToLowerInvariant (rare, since it lowercases).

Related errors

• plugin_create_failed
• unsupported_format
• Source range has no data
• Source range has no data rows
• Workbook is missing

AI-assisted analysis of iOfficeAI/OfficeCLI@1ced45e900 (2026-08-13). Data as JSON: /api/errors/1deed893a9d325aa. Report an issue: GitHub.