dotnet/wpf · error · InvalidOperationException

Animation_Invalid_DefaultValue

Animation_Invalid_DefaultValue

Error message

SR.Animation_Invalid_DefaultValue (Animation_Invalid_DefaultValue)

What it means

ByteAnimation.GetCurrentValueCore throws InvalidOperationException when the animation must supply a default origin value (validateOrigin is true and defaultOriginValue was not provided) but that value is not a valid animation value for Byte (per AnimatedTypeHelpers.IsValidAnimationValueByte). WPF refuses to guess an origin for the animated Byte because no valid starting value exists.

Solutions

Set the From property on the ByteAnimation so an explicit origin exists
Pass a valid byte defaultOriginValue when calling GetCurrentValueCore
Ensure the target property has a valid base value before the animation runs

Example fix

// before
var anim = new ByteAnimation { To = 100 };
animation.BeginAnimation(byteProperty, anim, null); // no origin value
// after
var anim = new ByteAnimation { From = 0, To = 100 };

Defensive patterns

Strategy: validation

Validate before calling

if (!anim.From.HasValue && (defaultOriginValue == null || !IsValidByte(defaultOriginValue)))
    anim.From = 0; // supply explicit origin before evaluating

Type guard

static bool HasValidOrigin(ByteAnimation a) => a.From.HasValue;

Try / catch

try { value = anim.GetCurrentValue(baseValue, null, clock, defaultClock); }
catch (InvalidOperationException) { /* missing/invalid origin: set From or base value */ }

Prevention

Always set From on From/To/By animations, or ensure the target property has a base value
Do not call GetCurrentValueCore directly with null default values unless another source exists
Initialize animated byte properties before starting the animation

When it happens

Trigger: Calling GetCurrentValue/GetCurrentValueCore with defaultOriginValue==null (or an invalid default) while the animation has no From value set and no prior/current value to use as origin.

Common situations: Animating a byte property where neither From nor a base value is available — e.g. animation targeting a property that has never been set, or manually invoking the animation API without origin/destination values.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/a0e30776b96bfc1e. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Animation/Generated/ByteAnimation.cs:313

                    if (IsAdditive)
                    {
                        foundation = defaultOriginValue;
                        validateOrigin = true;
                    }

                    break;

                default:

                    Debug.Fail("Unknown animation type.");

                    break;
            }

            if (validateOrigin 
                && !AnimatedTypeHelpers.IsValidAnimationValueByte(defaultOriginValue))
            {
                throw new InvalidOperationException(
                    SR.Format(
                        SR.Animation_Invalid_DefaultValue,
                        this.GetType(),
                        "origin",
                        defaultOriginValue.ToString(CultureInfo.InvariantCulture)));
            }

            if (validateDestination 
                && !AnimatedTypeHelpers.IsValidAnimationValueByte(defaultDestinationValue))
            {
                throw new InvalidOperationException(
                    SR.Format(
                        SR.Animation_Invalid_DefaultValue,
                        this.GetType(),
                        "destination",
                        defaultDestinationValue.ToString(CultureInfo.InvariantCulture)));
            }

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