dotnet/wpf · error · InvalidOperationException

SR.NoElementObject

Error message

SR.NoElementObject

What it means

FixedTextPointer.ReadLocalValue requires the pointer to be scoped to a text element of the FixedElement tree. If the scoping element is not a text element (e.g. the pointer sits at a non-element position), an InvalidOperationException(SR.NoElementObject) is thrown because there is no element object to read a local value from.

Solutions

  1. Ensure the pointer is positioned inside a text element (e.g. use TextElement boundary positions) before calling ReadLocalValue.
  2. Check the scoping element's IsTextElement via your own navigation logic before reading values.
  3. Read the property from the FixedElement/page object directly instead of through the pointer.
  4. Catch InvalidOperationException and treat the value as unset.

Example fix

// before
var value = pointer.ReadLocalValue(MyProperty); // may throw at non-text positions
// after
if (IsInsideTextElement(pointer)) { var value = pointer.ReadLocalValue(MyProperty); }
Defensive patterns

Strategy: try-catch

Validate before calling

// No public pre-check; guard by only calling ReadLocalValue on pointers known to sit within a text element.
bool isTextElementScoped = /* your position bookkeeping */;

Try / catch

try { value = pointer.ReadLocalValue(property); }
catch (InvalidOperationException) { value = DependencyProperty.UnsetValue; }

Prevention

When it happens

Trigger: Calling ReadLocalValue on a FixedTextPointer whose FlowPosition's scoping element is not a text element — e.g. a pointer at the document root or positioned between structural elements.

Common situations: Using pointers created at document-level offsets rather than within a Glyphs/Paragraph text element; querying dependency property values on pointers after the element tree changed.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/c60e267058b017b7. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Documents/FixedTextPointer.cs:209

        {
            ArgumentNullException.ThrowIfNull(property);

            FixedElement e = _flowPosition.GetScopingElement();
            return e.GetValue(property);
        }

        /// <summary>
        /// <see cref="ITextPointer.ReadLocalValue"/>
        /// </summary>
        /// <remarks>Throws InvalidOperationException if there is no scoping element</remarks>
        object ITextPointer.ReadLocalValue(DependencyProperty property)
        {
            ArgumentNullException.ThrowIfNull(property);

            FixedElement e = _flowPosition.GetScopingElement();
            if (!e.IsTextElement)
            {
                throw new InvalidOperationException(SR.NoElementObject);
            }

            return e.ReadLocalValue(property);
        }

        /// <summary>
        /// <see cref="ITextPointer.GetLocalValueEnumerator"/>
        /// </summary>
        /// <remarks>Returns an empty enumerator if there is no scoping element</remarks>
        LocalValueEnumerator ITextPointer.GetLocalValueEnumerator()
        {
            FixedElement e = _flowPosition.GetScopingElement();

            if (!e.IsTextElement)
            {
                return (new DependencyObject()).GetLocalValueEnumerator();
            }

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