What causes "(no message) InvalidOperationException()" in dotnet/wpf?

Balance every PopMenuMode with exactly one PushMenuMode; track your own nesting count if paths can overlap.

dotnet/wpf · error · InvalidOperationException

(no message) InvalidOperationException()

Error message

(no message) InvalidOperationException()

What it means

InputManager.PopMenuMode throws a parameterless InvalidOperationException when _menuModeCount is zero or negative, meaning PopMenuMode was called more times than PushMenuMode. Menu mode is a ref-counted nesting; popping without a matching push breaks the internal invariant that the stack of menu sites is balanced.

Solutions

Balance every PopMenuMode with exactly one PushMenuMode; track your own nesting count if paths can overlap.
Check that cleanup/dispose logic does not call PopMenuMode redundantly (use a pushed flag).
Catch InvalidOperationException around the pop as a defensive guard in interop-heavy code, but fix the imbalance.

Example fix

// before
closeHandler += () => site.PopMenuMode(); // may run twice
// after
if (!_menuPushed) return;
_menuPushed = false;
site.PopMenuMode();

Defensive patterns

Strategy: try-catch

Validate before calling

if (_menuModeCount <= 0) return; // track your own push count alongside InputManager's

Try / catch

try { inputManager.PopMenuMode(menuSite); }
catch (InvalidOperationException) { /* unbalanced pop; log and continue */ }

Prevention

Maintain your own boolean/count so each PushMenuMode is popped exactly once.
Guard cleanup paths so error and close handlers do not both pop.
In menu interop, handle WM_EXITMENULOOP idempotently.

When it happens

Trigger: Calling PopMenuMode on an HwndSource/InputManager pair without a preceding PushMenuMode, or calling it twice after one push, e.g. in custom popup/menu interop code or double-dispose logic.

Common situations: Custom menu/popup hosting code that pushes on one path but pops on several (error + cleanup paths both popping); re-entrant close handlers; interop with Win32 menus where WM_EXITMENULOOP arrives more than once.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/996b43c1d1c12b30. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/InputManager.cs:353

                EventHandler enterMenuMode = EnterMenuMode;
                if (null != enterMenuMode)
                {
                    enterMenuMode(null, EventArgs.Empty);
                }
            }
        }

        /// <summary>
        ///     Controls call this to leave menu mode.
        ///</summary>
        public void PopMenuMode(PresentationSource menuSite)
        {
            ArgumentNullException.ThrowIfNull(menuSite);
            menuSite.VerifyAccess();

            if (_menuModeCount <= 0)
            {
                throw new InvalidOperationException();
            }

            menuSite.PopMenuMode();
            _menuModeCount -= 1;

            if (0 == _menuModeCount)
            {
                EventHandler leaveMenuMode = LeaveMenuMode;
                if (null != leaveMenuMode)
                {
                    leaveMenuMode(null, EventArgs.Empty);
                }
            }
        }

        /// <summary>
        ///     Returns whether or not the input manager is in menu mode.
        ///</summary>

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