Fix issue 15093: Removing multiple rows while selecting the last new-item row in DataGridView leads to exception

[SimonZhao888]

Fixes #15093

Root Cause

When deleting a selected row that includes the final "new item" row (the asterisk row), the bound data source may trigger an additional ItemAdded event. At this point, the number of items in the data source exceeds the number of bound rows in DataGridView.Rows, causing the row collection and the CurrencyManager state to fall out of sync. If the asterisk row is clicked again, the existing code treats this state as invalid and throws an InvalidOperationException.

Proposed changes

• In ProcessDeleteKey, strengthen the handling of the "selection includes a new row" scenario: only invoke DeleteRow(NewRowIndex) to clean up the pending new-row transaction when a valid AddNew transaction exists and the index is valid.
• Add boundary checks in DataGridViewDataConnection.GetError(int rowIndex) and DataGridViewDataConnection.GetError(int boundColumnIndex, int columnIndex, int rowIndex):
  • Return string.Empty immediately if CurrencyManager is null or rowIndex >= CurrencyManager.Count to prevent out-of-bounds access.
• Preserve the semantics of existing exception-handling branches; avoid replacing the core logic with a crude refresh mechanism that would introduce "blank ghost rows."

Customer Impact

• The default DataGridView error dialog no longer appears when users perform multiple batch deletions to clear the grid and then click "Add New Row" to re-enter data.
• Complex interactions involving row deletion are now more stable, reducing exceptions and state inconsistencies caused by residual transaction data.
• The data entry workflow is smoother, preventing interruptions caused by out-of-bounds exceptions.

Regression?

• No

Risk

• Mini

Screenshots

Before

Recording.2026-09-16.095825.mp4

After

Recording.2026-09-16.152747.mp4

Test methodology

• Manual

Test environment(s)

• 11.0.100-rc.1.26420.103

Microsoft Reviewers: Open in CodeFlow

[Copilot]

🟡 Changes recommended

A moderate issue and a regression-test gap remain unresolved.

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Pull request overview

Fixes DataGridView synchronization failures when deleting rows involving the final new-item row.

Changes:

• Rebuilds bound rows for out-of-sync ItemAdded events.
• Restores new-item row synchronization.

File summaries

File	Summary	Findings
src/System.Windows.Forms/System/Windows/Forms/Controls/DataGridView/DataGridView.DataConnection.cs	Handles row resynchronization after affected ItemAdded events.	Moderate (1 vote): Preserve or recompute the initiating row/current position across refresh. Nit (3 votes): Add a regression test for the reported sequence.

Review details

Suppressed comments (1)

src/System.Windows.Forms/System/Windows/Forms/Controls/DataGridView/DataGridView.DataConnection.cs:607

• Rebuilding here changes NewRowIndex while OnRowEnter is still processing the cell that initiated AddNew. RefreshRows clears and repopulates the rows, then PushAllowUserToAddRows appends the new-item row, so the original rowIndex (the old asterisk row) now points at the phantom item. When OnRowEnter resumes at DataGridView.Methods.cs:17773, DataConnection.OnRowEnter can move the currency position back to that old index, leaving focus/editing on the phantom row instead of the newly added item. Preserve or recompute the initiating row/current position across this refresh.

                                _owner.RefreshRows(scrollIntoView: !_owner.InSortOperation);

• Files reviewed: 1/1 changed files
• Comments generated: 1
• Review effort level: Lite

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 37.24166%. Comparing base (60135a0) to head (f83d7a9).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@              Coverage Diff              @@
##                main      #15117   +/-   ##
=============================================
  Coverage   37.24166%   37.24166%           
=============================================
  Files            246         246           
  Lines           9774        9774           
  Branches        1029        1029           
=============================================
  Hits            3640        3640           
  Misses          5970        5970           
  Partials         164         164           

Flag	Coverage Δ
Debug	37.24166% <ø> (ø)
production	39.36526% <ø> (ø)
test	20.64923% <ø> (ø)
unit	39.36526% <ø> (ø)

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[Copilot]

🟡 Changes recommended

Moderate issues remain in exception handling and regression-test coverage.

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Review details

Suppressed comments (1)

src/System.Windows.Forms/System/Windows/Forms/Controls/DataGridView/DataGridView.Methods.cs:20008

• The new test never enters the * row, so it leaves IsInAddNewTransaction false and skips the new branch at lines 20006-20014. It would pass against the base implementation and does not reproduce the hidden pending item, the subsequent move away, or the second *-row activation that triggers #15093. Add the reported sequence and assert that the second activation does not throw and that the list and bound-row counts remain synchronized.

• Files reviewed: 3/3 changed files
• Comments generated: 2
• Review effort level: Lite