dotnet/wpf · error · InvalidOperationException

SR.Image_NoArgument

Error message

SR.Image_NoArgument

What it means

CroppedBitmap crops a region of a Source bitmap; without a source there is nothing to crop. When EndInit finalizes creation and Source is null, IsValidForFinalizeCreation throws an InvalidOperationException (Image_NoArgument with "Source").

Solutions

1. Set Source to a loaded, non-null BitmapSource before EndInit
2. Ensure the source BitmapSource is fully initialized (its own EndInit completed) before assigning
3. For async loads, create the CroppedBitmap in the load-completed callback

Example fix

// before
var crop = new CroppedBitmap();
crop.BeginInit();
crop.SourceRect = new Int32Rect(0, 0, 100, 100);
crop.EndInit(); // throws
// after
var crop = new CroppedBitmap();
crop.BeginInit();
crop.Source = new BitmapImage(new Uri("photo.png"));
crop.SourceRect = new Int32Rect(0, 0, 100, 100);
crop.EndInit();

if (crop.Source == null) throw new ArgumentException("Source required", nameof(source));
if (crop.Source is BitmapImage bi && bi.IsDownloading) throw new InvalidOperationException("Wait for the source to finish loading");

static bool ReadyToCrop(BitmapSource s) => s != null && !((s as BitmapImage)?.IsDownloading ?? false);

try { crop.EndInit(); }
catch (InvalidOperationException ex) when (ex.Message.Contains("Source")) { Log("CroppedBitmap created without Source"); return fallbackCrop; }

When it happens

Trigger: new CroppedBitmap { SourceRect = new Int32Rect(...) } with BeginInit/EndInit but Source never set; setting only SourceRect in XAML; Source binding not yet resolved at EndInit.

Common situations: XAML binding to a bitmap loaded asynchronously; forgetting the Source line in code-built deferred init; copy-paste of SourceRect setup without the source assignment.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Image_NeitherArgument (UriSource, StreamSource)
• SR.Image_NoArgument
• SR.Image_NoArgument
• Cannot initialize compressor.
• Image_EncoderNoColorContext

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/d2374abf42d2ef67. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Imaging/CroppedBitmap.cs:154

        /// </summary>
        private void SourcePropertyChangedHook(DependencyPropertyChangedEventArgs e)
        {
            if (!e.IsASubPropertyChange)
            {
                BitmapSource newSource = e.NewValue as BitmapSource;
                _source = newSource;
                RegisterDownloadEventSource(_source);
                _syncObject = (newSource != null) ? newSource.SyncObject : _bitmapInit;
            }
        }

        internal override bool IsValidForFinalizeCreation(bool throwIfInvalid)
        {
            if (Source == null)
            {
                if (throwIfInvalid)
                {
                    throw new InvalidOperationException(SR.Format(SR.Image_NoArgument, "Source"));
                }
                return false;
            }

            return true;
        }

        /// <summary>
        ///     Notification on source rect changing.
        /// </summary>
        private void SourceRectPropertyChangedHook(DependencyPropertyChangedEventArgs e)
        {
            if (!e.IsASubPropertyChange)
            {
                _sourceRect = (Int32Rect)e.NewValue;
            }
        }

View on GitHub (pinned to 81131a70a4)