Flow-Launcher/Flow.Launcher · warning · InvalidOperationException

Invalid corner type

Error message

Invalid corner type

What it means

Thrown as InvalidOperationException from DWMSetCornerPreferenceForWindow when the supplied cornerType string does not match any of the four accepted literal values: 'DoNotRound', 'Round', 'RoundSmall', 'Default'. The switch expression's default arm throws because the value cannot be mapped to a DWM_WINDOW_CORNER_PREFERENCE enum.

Source

Thrown at Flow.Launcher.Infrastructure/Win32Helper.cs:105

                &darkMode,
                (uint)Marshal.SizeOf<int>()).Succeeded;
        }

        /// <summary>
        ///
        /// </summary>
        /// <param name="window"></param>
        /// <param name="cornerType">DoNotRound, Round, RoundSmall, Default</param>
        /// <returns></returns>
        public static unsafe bool DWMSetCornerPreferenceForWindow(Window window, string cornerType)
        {
            var preference = cornerType switch
            {
                "DoNotRound" => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_DONOTROUND,
                "Round" => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_ROUND,
                "RoundSmall" => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_ROUNDSMALL,
                "Default" => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_DEFAULT,
                _ => throw new InvalidOperationException("Invalid corner type")
            };

            return PInvoke.DwmSetWindowAttribute(
                GetWindowHandle(window),
                DWMWINDOWATTRIBUTE.DWMWA_WINDOW_CORNER_PREFERENCE,
                &preference,
                (uint)Marshal.SizeOf<int>()).Succeeded;
        }

        #endregion

        #region Wallpaper

        public static unsafe string GetWallpaperPath()
        {
            var wallpaperPtr = stackalloc char[(int)PInvoke.MAX_PATH];
            PInvoke.SystemParametersInfo(SYSTEM_PARAMETERS_INFO_ACTION.SPI_GETDESKWALLPAPER, PInvoke.MAX_PATH,
                wallpaperPtr,

View on GitHub (pinned to 7fc63b07bb)

Solutions

1. Set WindowCornerType to one of the exact literals: 'DoNotRound', 'Round', 'RoundSmall', or 'Default' (case-sensitive).
2. If loading from a theme/settings file, validate the value against the allowed set before calling this method.
3. Update Flow Launcher to a version that supports the corner type you intend to use.
4. Reset the setting to 'Default' and re-apply.

Example fix

// before
var preference = cornerType switch
{
    "DoNotRound" => ..., "Round" => ..., "RoundSmall" => ..., "Default" => ...,
    _ => throw new InvalidOperationException("Invalid corner type")
};

// after — case-insensitive match with a safe default + log
var preference = cornerType?.Trim() switch
{
    "DoNotRound" or "donotround" => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_DONOTROUND,
    "Round"      or "round"      => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_ROUND,
    "RoundSmall" or "roundsmall" => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_ROUNDSMALL,
    _ => DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_DEFAULT
};

var allowed = new[] { "DoNotRound", "Round", "RoundSmall", "Default" };
if (!allowed.Contains(cornerType))
{ Log.Warn(...); cornerType = "Default"; }

static bool IsValidCornerType(string s) =>
    s is "DoNotRound" or "Round" or "RoundSmall" or "Default";

try { Win32Helper.DWMSetCornerPreferenceForWindow(window, cornerType); }
catch (InvalidOperationException) { Win32Helper.DWMSetCornerPreferenceForWindow(window, "Default"); }

When it happens

Trigger: A theme XAML or settings value specifies a WindowCornerType that is misspelled, differently cased (e.g. 'round', 'donotround'), localized, or a legacy value from an older version; a user hand-edited settings.json and typed an invalid corner type; a future version adds a new corner type string that this build doesn't recognize.

Common situations: Manual settings.json edit with a typo or wrong case; theme authored against a newer Flow Launcher version using a corner name not yet supported; locale-specific value ('Redondo') accidentally saved; copy-paste of a corner name from docs that don't match the code's literals.

Related errors

• Theme path can't be found <{path}>
• DoublePinyinSchema '{schemaKey}' is invalid or double pinyin
• The zip file does not contain a plugin.json file.
• Invalid SVG dimensions: Height must be greater than zero in
• Failed to get IShellItemImageFactory

AI-assisted analysis of Flow-Launcher/Flow.Launcher@7fc63b07bb (2026-08-13). Data as JSON: /api/errors/773b1c1e69d9713c. Report an issue: GitHub.