dotnet/wpf · error · InvalidOperationException

SR.Touch_DeviceAlreadyActivated

Error message

SR.Touch_DeviceAlreadyActivated

What it means

TouchDevice.Activate registers the touch device with the input system (AddActiveDevice, AttachTouchDevice, Synchronize). A device may only be activated once; if _isActive is already true, Activate throws InvalidOperationException(Touch_DeviceAlreadyActivated). This is a state-machine guard: double activation would corrupt the active-device list and event routing.

Solutions

1. Track activation state in your device wrapper and call Activate() only when it has never been activated or after a successful Deactivate().
2. Structure the provider so Activate is invoked exactly once from a single lifecycle hook (e.g. OnTabletAdded), not from every input report.
3. Wrap the call so re-activation is a no-op instead of an exception path.

Example fix

// before
protected override void OnCreated()
{
    Activate();
}
protected override void OnEnabled() // may fire after OnCreated
{
    Activate(); // InvalidOperationException: already activated
}

// after
private bool _activated;
private void EnsureActivated()
{
    if (!_activated)
    {
        Activate();
        _activated = true;
    }
}

if (device.IsActive) return; // skip Activate when already active

try { device.Activate(); }
catch (InvalidOperationException ex) when (ex.Message.Contains("activated"))
{
    // already active — treat as success
}

When it happens

Trigger: Calling Activate() (from a TouchDevice subclass, e.g. a custom stylus/touch provider) a second time without an intervening Deactivate(); calling Activate from both a touchdown handler and an initialization path; re-activating after a reset that did not actually clear _isActive.

Common situations: Custom touch/stylus integration code (e.g. simulated touch drivers, Windows Ink interop) that activates the device in multiple lifecycle callbacks; re-entrancy when the same device is reported by several input reports; test harnesses activating fixtures repeatedly.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• SR.Touch_DeviceNotActivated
• SR.Manipulation_ManipulationNotEnabled
• Animation_Invalid_DefaultValue
• ArgumentOutOfRangeException(nameof(value))
• ArgumentOutOfRangeException(nameof(value))

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/28bb8a5a9b6e0305. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/TouchDevice.cs:694

                _reevaluateOver = null;

                OnHitTestInvalidatedAsync(this, EventArgs.Empty);
            }

            bool handled = RaiseTouchUp();
            _isDown = false;
            UpdateDirectlyOver(isSynchronize: false);
            OnUpdated();

            Touch.ReportFrame();
            return handled;
        }

        protected void Activate()
        {
            if (_isActive)
            {
                throw new InvalidOperationException(SR.Touch_DeviceAlreadyActivated);
            }

            PromotingToManipulation = false;
            AddActiveDevice(this);
            AttachTouchDevice();
            Synchronize();

            if (_activeDevices.Count == 1)
            {
                _isPrimary = true;
            }

            _isActive = true;

            if (Activated != null)
            {
                Activated(this, EventArgs.Empty);
            }

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