Fix data binding fallback update for uncreated controls

[abineshPalanisamy]

Fixes #13470

Proposed changes

• Update Binding.PushData(bool force) to avoid calling SetPropValue(null) when the binding is inactive and the target component has not yet been created.
• Preserve the existing fallback behavior for inactive bindings when the target component is already created.
• Add regression coverage in BindingTests for a bound NumericUpDown hosted on an inactive TabPage, where the target control is not yet created and a shared binding manager pushes updates to all bindings.
• Add test coverage to verify that the binding still works correctly after the inactive tab page is selected and the target control becomes create

Root cause

• The issue occurs when multiple controls are bound to the same data source and share the same BindingManagerBase.
• When one bound control updates the data source, BindingManagerBase.PushData() attempts to push data to all associated bindings.
• For a control hosted on an inactive TabPage, the target control may not be created yet.
• In this state, the binding is inactive (IsBinding == false), but Binding.PushData(bool force) still executes the fallback path and calls SetPropValue(null).
• For value-type target properties, this null assignment can be converted to a default value, such as 0.
• In the reported scenario, NumericUpDown.Minimum is set to 8, so assigning 0 to NumericUpDown.Value causes ArgumentOutOfRangeException.

Customer Impact

• Fixes a crash that can occur when a data-bound NumericUpDown is hosted inside an inactive or invisible container, such as an unselected TabPage.
• Prevents invalid fallback/default values from being pushed into controls that are not yet created.
• Improves reliability for applications that use data binding across multiple controls sharing the same data source.
• Preserves existing behavior for inactive bindings whose target components are already created.

Regression?

• No

Risk

• Low.
• The change is limited to the inactive binding fallback path in Binding.PushData(bool force).
• Existing behavior is preserved for active bindings.
• No public API changes.
• No layout, rendering, accessibility, or designer behavior changes.

Screenshots

Before

Databinding_Before_fix.mp4

After

Databinding_After_fix.mp4

Test methodology

• Reproduced the issue scenario described in the GitHub issue:

  • A TabControl contains two TabPage instances.
  • Each tab contains a NumericUpDown.
  • Both controls are bound to the same data source.
  • The second NumericUpDown is placed on an inactive tab page and has Minimum set to 8.
  • Changing the first NumericUpDown triggers a binding update through the shared BindingManagerBase.
  • Before the fix, this causes ArgumentOutOfRangeException because the inactive binding path pushes an invalid fallback value to the uncreated target control.

• Verified that the updated Binding.PushData(bool force) behavior avoids calling SetPropValue(null) when the target component has not yet been created.

• Added unit test coverage in BindingTests to validate that:

  • changing a bound control on the active tab does not throw when another bound NumericUpDown is on an inactive tab;
  • the inactive tab control receives the correct bound value after the tab is selected and the control becomes created;
  • the fix covers the binding lifecycle issue without changing the broader binding flow.

• Verified that the existing inactive-binding fallback behavior is preserved when the target component is already created.

Accessibility testing

Test environment(s)

• 11.0.100-preview.3.26170.106

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Pull request overview

This PR fixes a WinForms data binding crash when BindingManagerBase.PushData() pushes updates to bindings whose target controls haven’t created their handles yet (e.g., controls hosted on an inactive TabPage). The change prevents the inactive-binding fallback path from pushing a null value into an uncreated control, which could otherwise coerce to an invalid default (like 0) and trigger ArgumentOutOfRangeException for value-type properties such as NumericUpDown.Value.

Changes:

• Guard Binding.PushData(bool force) so the inactive-binding fallback (SetPropValue(null)) only runs when the target component is already created.
• Add regression tests covering a bound NumericUpDown on an inactive tab page (no throw during shared manager updates; correct value after tab activation).
• Add a test ensuring Binding.ReadValue() does not throw for an uncreated NumericUpDown with Minimum set.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/System.Windows.Forms/System/Windows/Forms/DataBinding/Binding.cs	Avoids calling SetPropValue(null) for inactive bindings when the target control isn’t created, preventing invalid fallback writes.
src/test/unit/System.Windows.Forms/System/Windows/Forms/BindingTests.cs	Adds regression coverage for inactive-tab NumericUpDown binding updates and uncreated-control ReadValue() behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.