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Some APIs throw ArgumentNullException

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Some APIs now validate input parameters and throw an ArgumentNullException where previously they threw a NullReferenceException, if invoked with null input arguments.

Change description

In previous .NET versions, the affected APIs throw a NullReferenceException if invoked with an argument that's null.

Starting in .NET 6, the affected APIs throw an ArgumentNullException if invoked with an argument that's null.

Change category

This change affects binary compatibility.

Reason for change

Throwing ArgumentNullException conforms to .NET Runtime behavior. It provides a better debug experience by clearly communicating which argument caused the exception.

Version introduced

.NET 6

  • Review and, if necessary, update your code to prevent passing null input arguments to the affected APIs.
  • If your code handles NullReferenceException, replace or add an additional handler for ArgumentNullException.

Affected APIs

The following table lists the affected APIs and specific parameters:

Method/property Parameter name
System.Windows.Forms.TreeNodeCollection.Item[Int32] index
DrawTreeNodeEventArgs(Graphics, TreeNode, Rectangle, TreeNodeStates) graphics
DataGridViewRowStateChangedEventArgs(DataGridViewRow, DataGridViewElementStates) dataGridViewRow
DataGridViewColumnStateChangedEventArgs(DataGridViewColumn, DataGridViewElementStates) dataGridViewColumn

See also