Description

Binding and MultiBinding have different behavior when return value's type not match targetType.

Reproduction Steps

<TextBlock>
  <TextBlock.Text>
    <Binding Converter="{StaticResource TestConverter}"/>
  </TextBlock.Text>
</TextBlock>

internal class TestConverter : IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
    return 0.46164641164;
  }

🆗

<TextBlock>
  <TextBlock.Text>
    <MultiBinding Converter="{StaticResource TestConverter}"/>
  </TextBlock.Text>
</TextBlock>

internal class TestConverter : IMultiValueConverter
{
  public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
  {
    return 0.46164641164;
  }

❌System.Windows.Data Error: 5 : Value produced by BindingExpression is not valid for target property. Double:'0.46164641164' MultiBindingExpression:target element is 'TextBlock' (Name=''); target property is 'Text' (type 'String')

Expected behavior

all 🆗

Actual behavior

Binding 🆗
MultiBinding ❌

Regression?

No response

Known Workarounds

No response

Impact

No response

Configuration

No response

Other information

No response