dotnet/wpf · error · ArgumentException

SR.InvalidPropertyValue formatted with (value, "Name") -…

Error message

SR.InvalidPropertyValue formatted with (value, "Name") - invalid Storyboard.Name value

What it means

BeginStoryboard.Name throws ArgumentException (SR.InvalidPropertyValue formatted with the bad value and "Name") when assigned a string that is not a valid XAML identifier name. This mirrors the validation DependencyObject.SetValueValidateParams performs; the name is used to register the storyboard for interactive control.

Solutions

Use a valid XAML name: start with a letter or underscore, contain only letters, digits, underscores.
Sanitize generated names (replace invalid characters, prefix with a letter) before assigning.
Validate with System.Windows.Markup.NameValidationHelper before setting.

Example fix

// before
beginStoryboard.Name = "my storyboard 1";
// after
beginStoryboard.Name = "MyStoryboard1";

Defensive patterns

Strategy: validation

Validate before calling

bool IsValidXamlName(string name) =>
    name != null && System.Text.RegularExpressions.Regex.IsMatch(name, "^[A-Za-z_][A-Za-z0-9_.]*$");
if (IsValidXamlName(candidateName)) beginStoryboard.Name = candidateName;

Try / catch

try { beginStoryboard.Name = name; }
catch (ArgumentException ex) { beginStoryboard.Name = SanitizeName(name); }

Prevention

Generate names that start with a letter or underscore and use only letters/digits/underscores
Sanitize user- or config-derived names before assigning to Name
Test XAML with names containing spaces or digits early

When it happens

Trigger: Setting BeginStoryboard.Name to a string containing invalid identifier characters (spaces, leading digits, punctuation, non-identifier symbols) as checked by NameValidationHelper.IsValidIdentifierName.

Common situations: XAML with a BeginStoryboard Name containing spaces or starting with a digit, or programmatically generating names from user input without sanitization.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/090e5a3b5c6a5804. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Media/Animation/BeginStoryboard.cs:105

    /// by a control action such as pause and resume.  Defaults to null, which
    /// means this storyboard is not going to be interactively controlled.
    /// </summary>
    // Null == no interactive control == "Fire and Forget"
    [DefaultValue(null)]
    public string Name
    {
        get
        {
            return _name;
        }
        set
        {
            ThrowIfSealed();

            if(value != null && !System.Windows.Markup.NameValidationHelper.IsValidIdentifierName(value))
            {
                // Duplicate the error string thrown from DependencyObject.SetValueValidateParams
                throw new ArgumentException(SR.Format(SR.InvalidPropertyValue, value, "Name"));
            }
            
            // Null is OK - it's to remove whatever name was previously set.
            _name = value;
        }
    }

    private void ThrowIfSealed()
    {
        if (IsSealed)
        {
            throw new InvalidOperationException(SR.Format(SR.CannotChangeAfterSealed, "BeginStoryboard"));
        }
    }
    
    // Bug #1329664 workaround to make beta 2
    // Remove thread affinity when sealed, but before doing that, snapshot the
    //  current Storyboard value and remove *its* thread affinity too.

View on GitHub (pinned to 81131a70a4)