What causes "SR.Image_NoArgument (Transform)" in dotnet/wpf?

Pass Transform.Identity instead of null when no transform is needed

dotnet/wpf · error · InvalidOperationException

SR.Image_NoArgument (Transform)

Error message

SR.Image_NoArgument (Transform)

What it means

The TransformedBitmap(source, transform) constructor requires both a non-null source and a non-null transform; a null transform yields no valid bitmap definition, so it throws InvalidOperationException with SR.Image_NoArgument("Transform"). The source null case is already handled by ArgumentNullException.ThrowIfNull.

Solutions

Pass Transform.Identity instead of null when no transform is needed
Use the source bitmap directly rather than wrapping in TransformedBitmap when no transform applies
Coalesce the nullable transform: new TransformedBitmap(source, transform ?? Transform.Identity)

Example fix

// before
Transform transform = GetOptionalTransform(); // may be null
var tb = new TransformedBitmap(source, transform);
// after
Transform transform = GetOptionalTransform() ?? Transform.Identity;
var tb = new TransformedBitmap(source, transform);

Defensive patterns

Strategy: validation

Validate before calling

if (transform == null)
    throw new ArgumentException("Transform must not be null", nameof(transform));

Type guard

static bool HasTransform(Transform t) => t != null;

Try / catch

try { var tb = new TransformedBitmap(source, transform); }
catch (InvalidOperationException ex) when (ex.Message.Contains("Transform"))
{ /* supply Transform.Identity fallback */ }

Prevention

Coalesce optional transforms with ?? Transform.Identity
Never pass raw nullable transform fields into bitmap constructors
Prefer BeginInit/EndInit with explicit property assignment so missing parts fail clearly

When it happens

Trigger: new TransformedBitmap(source, transform) where a nullable Transform variable is null — e.g. an optional transform resolved to null, or a transform factory returned null before the constructor call.

Common situations: Optional rotation logic that skips assignment when no rotation is needed; transform created from deserialized/config data that failed to resolve; BeginInit-style code refactored into direct construction with an unset Transform property.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/cf956d4a98d016f1. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Imaging/TransformedBitmap.cs:36

        /// </summary>
        public TransformedBitmap()
            : base(true) // Use base class virtuals
        {
        }

        /// <summary>
        /// Construct a TransformedBitmap with the given newTransform
        /// </summary>
        /// <param name="source">BitmapSource to apply to the newTransform to</param>
        /// <param name="newTransform">Transform to apply to the bitmap</param>
        public TransformedBitmap(BitmapSource source, Transform newTransform)
            : base(true) // Use base class virtuals
        {
            ArgumentNullException.ThrowIfNull(source);

            if (newTransform == null)
            {
                throw new InvalidOperationException(SR.Format(SR.Image_NoArgument, "Transform"));
            }

            if (!CheckTransform(newTransform))
            {
                throw new InvalidOperationException(SR.Image_OnlyOrthogonal);
            }

            _bitmapInit.BeginInit();

            Source = source;
            Transform = newTransform;

            _bitmapInit.EndInit();
            FinalizeCreation();
        }

        // ISupportInitialize

View on GitHub (pinned to 81131a70a4)