NickeManarin/ScreenToGif · error · Exception

It was not possible to get a list of known screens.

Error message

It was not possible to get a list of known screens.

What it means

NewRecorder centers the recorder panel when the region is empty by picking a screen from _viewModel.Monitors (the one under the cursor, else the primary, else any). If Monitors is empty the whole chain returns null and it throws — there is literally no enumerated display to center on.

Source

Thrown at ScreenToGif/Windows/NewRecorder.xaml.cs:898

            }

            #endregion
        }

        //Change the scale of the sizing controls.
        WidthIntegerBox.Scale = UserSettings.All.SelectedRegionScale;
        HeightIntegerBox.Scale = UserSettings.All.SelectedRegionScale;

        #region Adjust the position of the main controls

        if (_viewModel.Region.IsEmpty)
        {
            #region Center on screen

            var screen = _viewModel.Monitors.FirstOrDefault(x => x.Bounds.Contains(CursorHelper.GetMousePosition(1, Left, Top))) ?? _viewModel.Monitors.FirstOrDefault(x => x.IsPrimary) ?? _viewModel.Monitors.FirstOrDefault();

            if (screen == null)
                throw new Exception("It was not possible to get a list of known screens.");

            MovePanelTo(screen, screen.WorkingArea.Left + screen.WorkingArea.Width / 2 - RecorderWindow.ActualWidth / 2, screen.WorkingArea.Top + screen.WorkingArea.Height / 2 - RecorderWindow.ActualHeight / 2);

            #endregion
        }
        else
        {
            MoveCommandPanel();
            DisplaySelection((ModeType) UserSettings.All.RecorderModeIndex);
        }

        #endregion
    }

    private void ForceUpdate()
    {
        InvalidateMeasure();
        InvalidateArrange();

View on GitHub (pinned to a4d0a67c21)

Solutions

1. Re-enumerate monitors before throwing — call the monitor detection code and rebuild _viewModel.Monitors.
2. Ensure at least one display is connected and powered on before opening the recorder.
3. If running over RDP/headless, attach a physical or virtual display.
4. Fall back to SystemParameters.PrimaryScreen / SystemInformation.VirtualScreen when Monitors is empty.

Example fix

// before
var screen = _viewModel.Monitors.FirstOrDefault(x => x.Bounds.Contains(CursorHelper.GetMousePosition(1, Left, Top))) ?? _viewModel.Monitors.FirstOrDefault(x => x.IsPrimary) ?? _viewModel.Monitors.FirstOrDefault();
if (screen == null)
    throw new Exception("It was not possible to get a list of known screens.");

// after
var screen = _viewModel.Monitors.FirstOrDefault(x => x.Bounds.Contains(CursorHelper.GetMousePosition(1, Left, Top))) ?? _viewModel.Monitors.FirstOrDefault(x => x.IsPrimary) ?? _viewModel.Monitors.FirstOrDefault();
if (screen == null)
    throw new Exception("It was not possible to get a list of known screens. No display detected — connect a monitor and reopen the recorder.");

if (_viewModel.Monitors == null || _viewModel.Monitors.Count == 0)
{
    await MonitorEnumerator.EnumerateAsync(); // re-populate _viewModel.Monitors
    if (_viewModel.Monitors.Count == 0) /* warn user: no display detected */
}

bool HasAnyMonitor => _viewModel.Monitors?.Any() == true;

try { /* center panel on screen */ }
catch (Exception ex) when (ex.Message.Contains("known screens"))
{ /* fall back to SystemParameters.PrimaryScreen or warn the user */ }

When it happens

Trigger: _viewModel.Region.IsEmpty AND _viewModel.Monitors is empty, so the FirstOrDefault(x => Bounds.Contains(...)) ?? FirstOrDefault(IsPrimary) ?? FirstOrDefault() chain yields null.

Common situations: Monitor enumeration returned no displays at recorder startup; all displays disconnected after launch; WMI/DXGI enumeration failed silently; headless session; service/context where no user desktop displays exist.

Related errors

• It was not possible to move the current selected region to t
• It was not possible to get a list of known screens.
• It was not possible to get a list of known screens.
• Could not find a proper output device for the area of L: {Le
• Impossible to capture the manual screenshot.

AI-assisted analysis of NickeManarin/ScreenToGif@a4d0a67c21 (2026-08-13). Data as JSON: /api/errors/f51d3f6e95fb4052. Report an issue: GitHub.