WinForms: Intermittent NullReferenceException When Accessing Controls in Form Closing Event
I'm stuck on something that should probably be simple. I'm a bit lost with I'm encountering an intermittent `NullReferenceException` when trying to access certain controls in my WinForms application during the `FormClosing` event. The specific code that triggers the exception looks like this: ```csharp private void MainForm_FormClosing(object sender, FormClosingEventArgs e) { if (myTextBox != null) // Accessing the TextBox { string input = myTextBox.Text; // Logic to save or process input } } ``` On some occasions, `myTextBox` ends up being `null`, even though it's clearly instantiated in the `Form_Load` method: ```csharp private void MainForm_Load(object sender, EventArgs e) { myTextBox = new TextBox(); // Other initialization code } ``` I have verified that the `Load` method is being called, and the form is properly displaying the `TextBox`. However, if the user closes the form quickly or if other asynchronous operations are happening, it appears that the `myTextBox` control might not be fully initialized or could be getting disposed before the `FormClosing` event is fired. I've tried checking if the control is not disposed or invoking my logic in a try-catch block to handle exceptions gracefully, but the `NullReferenceException` still occurs. I've also ensured that all event handlers are properly wired up and there are no race conditions. Is there a best practice to ensure that controls are accessible during the `FormClosing` event? Or is there a way to safely narrow down why `myTextBox` might be `null` at that point? Any insights or suggestions would be greatly appreciated! I recently upgraded to Csharp 3.9. I'd love to hear your thoughts on this. I'm working in a Debian environment. Thanks for taking the time to read this! I'm open to any suggestions.