Question

I’m using/building Scintilla.NET and switched the project to .NET 2.0 for compatibility issues.

It works, but when I click the new tab button I get an error which says:

Object reference not set to an
instance of an object.

The problem occurs in this code:

ScintillaNet.Scintilla currentScin;
Stream Stream1;

public List <ScintillaNet.Scintilla> ScinList;

//Code for various events

private void New_Click(object sender, EventArgs e)
{
    TabPage tabp = new TabPage();
    ScintillaNet.Scintilla scin = new ScintillaNet.Scintilla();
    scin.Dock = DockStyle.Fill;

    scin.Margins[0].Width = 20;
    scin.ConfigurationManager.CustomLocation = "My Styles";
    scin.ConfigurationManager.Language = "lua";

    scin.Parent = tabp;

    // This line throws "Object reference not set to an instance of an object."
    ScinList.Add(scin);

    tabControl1.TabPages.Add(tabp);
}

Answer 1

The problem is that you have not initialized ScinList. Fields of a class are initialized to their default value, which in this case is null.

You need to initialize it somewhere, either where it is declared…

public List<ScintillaNet.Scintilla> ScinList = new List<ScintillaNet.Scintilla>();

… or in the constructor …

public CLASSNAMEHERE()
{
    ScinList = new List<ScintillaNet.Scintilla>();
}

If this line actually does appear in your code, please edit your question with the code that does so.