dotnet/wpf · error · InvalidOperationException

SR.ProgressBarReadOnly

Error message

SR.ProgressBarReadOnly

What it means

IRangeValueProvider.SetValue on ProgressBarAutomationPeer unconditionally throws InvalidOperationException with SR.ProgressBarReadOnly because a ProgressBar is a read-only indicator — its value is driven by the application, never set by UIA clients. The peer also advertises IsReadOnly=true via the RangeValue pattern.

Solutions

1. Do not set progress via UIA; update ProgressBar.Value (or the bound view-model property) from application code.
2. Use only RangeValuePattern.Value to read progress in tests; simulate work through the app's API/view-model instead.
3. Remove ProgressBar from the list of RangeValue targets in generic automation harnesses.

Example fix

// before (test)
rangeValuePattern.SetValue(50.0); // always throws
// after
var current = rangeValuePattern.Value; // read-only
viewModel.Progress = 50; // drive progress from the app

if (rangeValuePattern.IsReadOnly) { /* never call SetValue on progress bars */ }

When it happens

Trigger: Any UIA client call to RangeValuePattern.SetValue() on a ProgressBar, regardless of state — there is no code path that allows it.

Common situations: Automation scripts that treat progress bars like sliders and attempt to set progress; generic pattern-exercising test harnesses that call SetValue on every RangeValue-capable element.

Related errors

• 0x80040209
• Cannot remove signature from read-only file.
• Cannot sign read-only file.
• CollectionIsFixedSize
• E_ACCESSDENIED

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/70f64225613615b5. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Automation/Peers/ProgressBarAutomationPeer.cs:47

        ///
        public override object GetPattern(PatternInterface patternInterface)
        {
            // Indeterminate ProgressBar should not support RangeValue pattern
            if (patternInterface == PatternInterface.RangeValue && ((ProgressBar)Owner).IsIndeterminate)
                return null;

            return base.GetPattern(patternInterface);
        }

        /// <summary>
        /// Request to set the value that this UI element is representing
        /// </summary>
        /// <param name="val">Value to set the UI to, as an object</param>
        /// <returns>true if the UI element was successfully set to the specified value</returns>
        //[CodeAnalysis("AptcaMethodsShouldOnlyCallAptcaMethods")] //Tracking Bug: 29647
        void IRangeValueProvider.SetValue(double val)
        {
            throw new InvalidOperationException(SR.ProgressBarReadOnly);
        }

        ///<summary>Indicates that the value can only be read, not modified.
        ///returns True if the control is read-only</summary>
        bool IRangeValueProvider.IsReadOnly
        {
            get
            {
                return true;
            }
        }

        ///<summary>Value of a Large Change</summary>
        double IRangeValueProvider.LargeChange
        {
            get
            {
                return double.NaN;

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