Code below, the blockId inserted into Viewport.Create, it returns viewport as null. Anyone know why?

[ed_sa]

sing Autodesk.Revit.Attributes;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Linq;
using System.Windows.Controls;
using System.Windows.Forms;
using Transaction = Autodesk.Revit.DB.Transaction;

namespace RevitAPI_JBA_Development_2022
{
[Transaction(TransactionMode.Manual)]
public class ImportDraftingViewsCommandSHORT : IExternalCommand
{
public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
{
UIApplication uiApp = commandData.Application;
UIDocument uiDoc = uiApp.ActiveUIDocument;
Autodesk.Revit.DB.Document currentDoc = uiDoc.Document;
ICollection<ElementId> copiedViewIds;

try
{
// Open a file dialog to select the external document
string externalDocumentPath = BrowseForFile(); // Path to your external document
// Implement your file dialog logic here

if (string.IsNullOrEmpty(externalDocumentPath))
{
TaskDialog.Show("Error", "No external document selected.");
return Result.Cancelled;
}

// Open the external document
Autodesk.Revit.DB.Document externalDoc = uiApp.Application.OpenDocumentFile(externalDocumentPath);

if (externalDoc == null)
{
TaskDialog.Show("Error", "Failed to open the external document.");
return Result.Failed;
}

// Get all drafting views from the external document
//FilteredElementCollector externalViewsCollector = new FilteredElementCollector(externalDoc)
// .OfClass(typeof(ViewDrafting));
List<ViewDrafting> externalViewsCollector = GetDraftingViews(externalDoc);
List<ViewSheet> viewSheets = GetSheets(currentDoc);

EfficientSelectDraftingViewFormFinalMultipleSHORT importedStuff = new EfficientSelectDraftingViewFormFinalMultipleSHORT(externalViewsCollector, viewSheets);
if (importedStuff.ShowDialog() != DialogResult.OK)
{
externalDoc.Close(false);
return Result.Cancelled;
}
ViewSheet selectedSheet = importedStuff.SelectedSheet;
List<ViewDrafting> selectedDraftingViews = importedStuff.SelectedDraftingViews;
ICollection<ElementId> elementIdsCollection = selectedDraftingViews
.Select(view => view.Id)
.Cast<ElementId>()
.ToList();

if (selectedDraftingViews != null)
{
using (Autodesk.Revit.DB.Transaction transaction = new Autodesk.Revit.DB.Transaction(currentDoc, "Transaction for all"))
{
try
{
transaction.Start();
// Iterate through each drafting view in the external document
foreach (ViewDrafting selectedDraftingView in selectedDraftingViews)
{
if (selectedDraftingView != null)
{
// Check if the drafting view is valid
if (!selectedDraftingView.IsValidObject)
{
TaskDialog.Show("Error", "The selected drafting view is invalid.");
transaction.RollBack();
return Result.Failed;
}
ElementId blockId;
// Duplicate the drafting view
using (Transaction externalTransaction = new Transaction(externalDoc, "ExternalDoc"))
{
externalTransaction.Start();
blockId = selectedDraftingView.Duplicate(ViewDuplicateOption.Duplicate);
externalTransaction.Commit();
}

if (blockId == null || blockId == ElementId.InvalidElementId)
{
TaskDialog.Show("Error", "Failed to duplicate the drafting view.");
transaction.RollBack();
return Result.Failed;
}

// Get the duplicated block element
Element block = externalDoc.GetElement(blockId);
if (block == null)
{
TaskDialog.Show("Error", "Failed to retrieve the duplicated drafting view.");
transaction.RollBack();
return Result.Failed;
}

// Create a viewport for the duplicated drafting view
Viewport viewport = Viewport.Create(currentDoc, selectedSheet.Id, blockId, XYZ.Zero);
if (viewport == null)
{
TaskDialog.Show("Error", "Failed to create viewport for the drafting view.");
transaction.RollBack();
return Result.Failed;
}
}
}
transaction.Commit();
externalDoc.Close(false);
return Result.Succeeded;
}
catch(Exception ex)
{
TaskDialog.Show("Error", $"{ex.Message}");
return Result.Failed;
}
}
}
return Result.Failed;
}
catch (Exception ex)
{
TaskDialog.Show("Error", $"{ex.Message}");
return Result.Failed;
}
}
private string BrowseForFile()
{
using (OpenFileDialog openFileDialog = new OpenFileDialog())
{
openFileDialog.Filter = "Revit Files (*.rvt)|*.rvt|All files(*.*)|*.*";
openFileDialog.FilterIndex = 1;
openFileDialog.RestoreDirectory = true;

if (openFileDialog.ShowDialog() == DialogResult.OK)
{
return openFileDialog.FileName;
}
else
{
return null;
}
}
}
private List<ViewDrafting> GetDraftingViews(Autodesk.Revit.DB.Document document)
{
List<ViewDrafting> draftingViews = new FilteredElementCollector(document)
.OfClass(typeof(ViewDrafting))
.Cast<ViewDrafting>()
.Where(v => v.IsTemplate == false)
.ToList();

return draftingViews;
}

public List<ViewSheet> GetSheets(Autodesk.Revit.DB.Document doc)
{
return new FilteredElementCollector(doc)
.OfClass(typeof(ViewSheet))
.Cast<ViewSheet>()
.ToList();
}
}
}

public class EfficientSelectDraftingViewFormFinalMultipleSHORT : System.Windows.Forms.Form
{
public System.Windows.Forms.ListBox draftingViewListBox;
public System.Windows.Forms.ComboBox sheetComboBox;
public System.Windows.Forms.Button okButton;
public System.Windows.Forms.Button cancelButton;
public ViewSheet SelectedSheet { get; private set; }
public List<ViewDrafting> importDraftingViewsFromExternalDoc;
public List<ViewSheet> sheets;
public List<ViewDrafting> SelectedDraftingViews { get; private set; }
private System.Drawing.Point lastLocation;

public EfficientSelectDraftingViewFormFinalMultipleSHORT(List<ViewDrafting> draftingViewsFromExternalDoc, List<ViewSheet> sheets)
{
try
{
this.importDraftingViewsFromExternalDoc = draftingViewsFromExternalDoc;
this.sheets = sheets;

InitializeComponent();

if (importDraftingViewsFromExternalDoc != null)
{
foreach (var draftingView in importDraftingViewsFromExternalDoc)
{
if (draftingView != null)
{
draftingViewListBox.Items.Add(draftingView.Name);
}
}
//Set the combo box style to allow multiple selection
draftingViewListBox.SelectionMode = System.Windows.Forms.SelectionMode.MultiSimple;
}

if (sheets != null)
{
foreach (var sheet in sheets)
{
sheetComboBox.Items.Add(sheet.Name);
}
}
}
catch (Exception ex)
{
TaskDialog.Show("Error", $"(twenty){ex.Message}");
}
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);

// Draw a circular border
e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
e.Graphics.DrawEllipse(Pens.Black, 0, 0, this.Width - 1, this.Height - 1);
}

private void InitializeComponent()
{
this.draftingViewListBox = new System.Windows.Forms.ListBox();
this.sheetComboBox = new System.Windows.Forms.ComboBox();
this.okButton = new System.Windows.Forms.Button();
this.cancelButton = new System.Windows.Forms.Button();

// Form
//this.FormBorderStyle = FormBorderStyle.SizableToolWindow;
this.ClientSize = new System.Drawing.Size(320, 320); // Set the form size to fit the circle
this.FormBorderStyle = FormBorderStyle.None; // Remove the border
this.StartPosition = FormStartPosition.CenterScreen; // Center the form on the screen

this.Paint += CircularBorderForm_Paint;
this.MouseDown += Form_MouseDown;
this.MouseMove += Form_MouseMove;
this.MouseUp += Form_MouseUp;

// Drafting View ListBox
this.draftingViewListBox.FormattingEnabled = true;
this.draftingViewListBox.Size = new System.Drawing.Size(200, 120); // Set size
this.draftingViewListBox.Location = new System.Drawing.Point(60, 50); // Position
this.draftingViewListBox.Name = "draftingViewListBox";
this.Controls.Add(this.draftingViewListBox);
this.draftingViewListBox.SelectionMode = System.Windows.Forms.SelectionMode.MultiExtended;
this.draftingViewListBox.KeyDown += listBox_KeyDown;

// Sheet ComboBox
this.sheetComboBox.FormattingEnabled = true;
this.sheetComboBox.Size = new System.Drawing.Size(200, 21); // Set size
this.sheetComboBox.Location = new System.Drawing.Point(60, 190); // Position
this.sheetComboBox.Name = "sheetComboBox";
this.Controls.Add(this.sheetComboBox);

// Ok Button
this.okButton.Location = new System.Drawing.Point(60, 230); // Position
this.okButton.Name = "okButton";
this.okButton.Size = new System.Drawing.Size(75, 23); // Set size
this.okButton.TabIndex = 0;
this.okButton.Text = "OK";
this.okButton.UseVisualStyleBackColor = true;
this.okButton.Click += new System.EventHandler(this.OkButton_Click);
this.Controls.Add(this.okButton);

// Cancel Button
this.cancelButton.Location = new System.Drawing.Point(185, 230); // Position
this.cancelButton.Name = "cancelButton";
this.cancelButton.Size = new System.Drawing.Size(75, 23); // Set size
this.cancelButton.TabIndex = 0;
this.cancelButton.Text = "Cancel";
this.cancelButton.UseVisualStyleBackColor = true;
this.cancelButton.Click += new System.EventHandler(this.CancelButton_Click);
this.Controls.Add(this.cancelButton);
}

private void CircularBorderForm_Paint(object sender, PaintEventArgs e)
{
// Create a circular region
GraphicsPath path = new GraphicsPath();
path.AddEllipse(0, 0, this.Width - 1, this.Height - 1);
Region = new Region(path);

// Dispose the GraphicsPath to free resources
path.Dispose();
}

private void Form_MouseDown(object sender, MouseEventArgs e)
{
lastLocation = e.Location;
}

private void Form_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
this.Left += e.X - lastLocation.X;
this.Top += e.Y - lastLocation.Y;
}
}

private void Form_MouseUp(object sender, MouseEventArgs e)
{
lastLocation = System.Drawing.Point.Empty;
}
private void OkButton_Click(object sender, EventArgs e)
{
SelectedDraftingViews = new List<ViewDrafting>(); // Initialize the list
string selectedSheetName = sheetComboBox.SelectedItem as string;

try
{
List<string> selectedDraftingViewNames = new List<string>();

if (!string.IsNullOrEmpty(selectedSheetName) && draftingViewListBox != null)
{
// Get the selected drafting views
foreach (var selectedItem in draftingViewListBox.SelectedItems)
{
if (selectedItem != null && !string.IsNullOrEmpty(selectedItem.ToString()))
{
if (importDraftingViewsFromExternalDoc != null)
{
var draftingView = importDraftingViewsFromExternalDoc.FirstOrDefault(x => x.Name == selectedItem.ToString());
if (draftingView != null)
{
SelectedDraftingViews.Add(importDraftingViewsFromExternalDoc.FirstOrDefault(x => x.Name == selectedItem.ToString()));
}
}
else
{
TaskDialog.Show("Error", "importDraftingViewsFromExternalDoc is null");
}
}
}

SelectedSheet = sheets.FirstOrDefault(sheet =>
sheet.Name?.Trim().Equals(selectedSheetName?.Trim(), StringComparison.OrdinalIgnoreCase) == true);

if (SelectedSheet == null)
{
TaskDialog.Show("Error", $"Selected sheet '{selectedSheetName}' not found.");
return;
}

this.DialogResult = DialogResult.OK;
this.Close();
}
}
catch (NullReferenceException nullEx)
{
TaskDialog.Show("Error", "A null reference exception occurred. Details: " + nullEx.Message);
}
catch (Exception ex)
{
TaskDialog.Show("Error", $"(21){ex.Message}");
}
}

private void listBox_KeyDown(object sender, KeyEventArgs e)
{
// Check if Ctrl+A is pressed
if (e.Control && e.KeyCode == Keys.A)
{
// Select all items
for (int i = 0; i < draftingViewListBox.Items.Count; i++)
{
draftingViewListBox.SetSelected(i, true);
}
}
else if (e.KeyCode == Keys.Escape) // Check if Escape key is pressed
{
// Deselect all items
draftingViewListBox.ClearSelected();
}
}

private void CancelButton_Click(object sender, EventArgs e)
{
DialogResult = DialogResult.Cancel;
Close();
}
}

[jeremy_tammik]

Your question would probably be more interesting to explore and easier to answer with more text and (a lot!) less code. 

Also, your code would be easier to read if you used the 'Insert code sample' button to format it.

[ed_sa]

you're right. Here is the code sample. Busy week, was laid off.Not achieving this project was part of that laid off issue haha.  here is the inserted code sample.

 Autodesk.Revit.Attributes;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Linq;
using System.Windows.Controls;
using System.Windows.Forms;
using Transaction = Autodesk.Revit.DB.Transaction;

namespace RevitAPI_JBA_Development_2022
{
[Transaction(TransactionMode.Manual)]
public class ImportDraftingViewsCommandSHORT : IExternalCommand
{
public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
{
UIApplication uiApp = commandData.Application;
UIDocument uiDoc = uiApp.ActiveUIDocument;
Autodesk.Revit.DB.Document currentDoc = uiDoc.Document;
ICollection<ElementId> copiedViewIds;

try
{
// Open a file dialog to select the external document
string externalDocumentPath = BrowseForFile(); // Path to your external document
// Implement your file dialog logic here

if (string.IsNullOrEmpty(externalDocumentPath))
{
TaskDialog.Show("Error", "No external document selected.");
return Result.Cancelled;
}

// Open the external document
Autodesk.Revit.DB.Document externalDoc = uiApp.Application.OpenDocumentFile(externalDocumentPath);

if (externalDoc == null)
{
TaskDialog.Show("Error", "Failed to open the external document.");
return Result.Failed;
}

// Get all drafting views from the external document
//FilteredElementCollector externalViewsCollector = new FilteredElementCollector(externalDoc)
// .OfClass(typeof(ViewDrafting));
List<ViewDrafting> externalViewsCollector = GetDraftingViews(externalDoc);
List<ViewSheet> viewSheets = GetSheets(currentDoc);

EfficientSelectDraftingViewFormFinalMultipleSHORT importedStuff = new EfficientSelectDraftingViewFormFinalMultipleSHORT(externalViewsCollector, viewSheets);
if (importedStuff.ShowDialog() != DialogResult.OK)
{
externalDoc.Close(false);
return Result.Cancelled;
}
ViewSheet selectedSheet = importedStuff.SelectedSheet;
List<ViewDrafting> selectedDraftingViews = importedStuff.SelectedDraftingViews;
ICollection<ElementId> elementIdsCollection = selectedDraftingViews
.Select(view => view.Id)
.Cast<ElementId>()
.ToList();

if (selectedDraftingViews != null)
{
using (Autodesk.Revit.DB.Transaction transaction = new Autodesk.Revit.DB.Transaction(currentDoc, "Transaction for all"))
{
try
{
transaction.Start();
// Iterate through each drafting view in the external document
foreach (ViewDrafting selectedDraftingView in selectedDraftingViews)
{
if (selectedDraftingView != null)
{
// Check if the drafting view is valid
if (!selectedDraftingView.IsValidObject)
{
TaskDialog.Show("Error", "The selected drafting view is invalid.");
transaction.RollBack();
return Result.Failed;
}
ElementId blockId;
// Duplicate the drafting view
using (Transaction externalTransaction = new Transaction(externalDoc, "ExternalDoc"))
{
externalTransaction.Start();
blockId = selectedDraftingView.Duplicate(ViewDuplicateOption.Duplicate);
externalTransaction.Commit();
}

if (blockId == null || blockId == ElementId.InvalidElementId)
{
TaskDialog.Show("Error", "Failed to duplicate the drafting view.");
transaction.RollBack();
return Result.Failed;
}

// Get the duplicated block element
Element block = externalDoc.GetElement(blockId);
if (block == null)
{
TaskDialog.Show("Error", "Failed to retrieve the duplicated drafting view.");
transaction.RollBack();
return Result.Failed;
}

// Create a viewport for the duplicated drafting view
Viewport viewport = Viewport.Create(currentDoc, selectedSheet.Id, blockId, XYZ.Zero);
if (viewport == null)
{
TaskDialog.Show("Error", "Failed to create viewport for the drafting view.");
transaction.RollBack();
return Result.Failed;
}
}
}
transaction.Commit();
externalDoc.Close(false);
return Result.Succeeded;
}
catch(Exception ex)
{
TaskDialog.Show("Error", $"{ex.Message}");
return Result.Failed;
}
}
}
return Result.Failed;
}
catch (Exception ex)
{
TaskDialog.Show("Error", $"{ex.Message}");
return Result.Failed;
}
}
private string BrowseForFile()
{
using (OpenFileDialog openFileDialog = new OpenFileDialog())
{
openFileDialog.Filter = "Revit Files (*.rvt)|*.rvt|All files(*.*)|*.*";
openFileDialog.FilterIndex = 1;
openFileDialog.RestoreDirectory = true;

if (openFileDialog.ShowDialog() == DialogResult.OK)
{
return openFileDialog.FileName;
}
else
{
return null;
}
}
}
private List<ViewDrafting> GetDraftingViews(Autodesk.Revit.DB.Document document)
{
List<ViewDrafting> draftingViews = new FilteredElementCollector(document)
.OfClass(typeof(ViewDrafting))
.Cast<ViewDrafting>()
.Where(v => v.IsTemplate == false)
.ToList();

return draftingViews;
}

public List<ViewSheet> GetSheets(Autodesk.Revit.DB.Document doc)
{
return new FilteredElementCollector(doc)
.OfClass(typeof(ViewSheet))
.Cast<ViewSheet>()
.ToList();
}
}
}

public class EfficientSelectDraftingViewFormFinalMultipleSHORT : System.Windows.Forms.Form
{
public System.Windows.Forms.ListBox draftingViewListBox;
public System.Windows.Forms.ComboBox sheetComboBox;
public System.Windows.Forms.Button okButton;
public System.Windows.Forms.Button cancelButton;
public ViewSheet SelectedSheet { get; private set; }
public List<ViewDrafting> importDraftingViewsFromExternalDoc;
public List<ViewSheet> sheets;
public List<ViewDrafting> SelectedDraftingViews { get; private set; }
private System.Drawing.Point lastLocation;

public EfficientSelectDraftingViewFormFinalMultipleSHORT(List<ViewDrafting> draftingViewsFromExternalDoc, List<ViewSheet> sheets)
{
try
{
this.importDraftingViewsFromExternalDoc = draftingViewsFromExternalDoc;
this.sheets = sheets;

InitializeComponent();

if (importDraftingViewsFromExternalDoc != null)
{
foreach (var draftingView in importDraftingViewsFromExternalDoc)
{
if (draftingView != null)
{
draftingViewListBox.Items.Add(draftingView.Name);
}
}
//Set the combo box style to allow multiple selection
draftingViewListBox.SelectionMode = System.Windows.Forms.SelectionMode.MultiSimple;
}

if (sheets != null)
{
foreach (var sheet in sheets)
{
sheetComboBox.Items.Add(sheet.Name);
}
}
}
catch (Exception ex)
{
TaskDialog.Show("Error", $"(twenty){ex.Message}");
}
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);

// Draw a circular border
e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
e.Graphics.DrawEllipse(Pens.Black, 0, 0, this.Width - 1, this.Height - 1);
}


private void InitializeComponent()
{
this.draftingViewListBox = new System.Windows.Forms.ListBox();
this.sheetComboBox = new System.Windows.Forms.ComboBox();
this.okButton = new System.Windows.Forms.Button();
this.cancelButton = new System.Windows.Forms.Button();

// Form
//this.FormBorderStyle = FormBorderStyle.SizableToolWindow;
this.ClientSize = new System.Drawing.Size(320, 320); // Set the form size to fit the circle
this.FormBorderStyle = FormBorderStyle.None; // Remove the border
this.StartPosition = FormStartPosition.CenterScreen; // Center the form on the screen


this.Paint += CircularBorderForm_Paint;
this.MouseDown += Form_MouseDown;
this.MouseMove += Form_MouseMove;
this.MouseUp += Form_MouseUp;

// Drafting View ListBox
this.draftingViewListBox.FormattingEnabled = true;
this.draftingViewListBox.Size = new System.Drawing.Size(200, 120); // Set size
this.draftingViewListBox.Location = new System.Drawing.Point(60, 50); // Position
this.draftingViewListBox.Name = "draftingViewListBox";
this.Controls.Add(this.draftingViewListBox);
this.draftingViewListBox.SelectionMode = System.Windows.Forms.SelectionMode.MultiExtended;
this.draftingViewListBox.KeyDown += listBox_KeyDown;

// Sheet ComboBox
this.sheetComboBox.FormattingEnabled = true;
this.sheetComboBox.Size = new System.Drawing.Size(200, 21); // Set size
this.sheetComboBox.Location = new System.Drawing.Point(60, 190); // Position
this.sheetComboBox.Name = "sheetComboBox";
this.Controls.Add(this.sheetComboBox);

// Ok Button
this.okButton.Location = new System.Drawing.Point(60, 230); // Position
this.okButton.Name = "okButton";
this.okButton.Size = new System.Drawing.Size(75, 23); // Set size
this.okButton.TabIndex = 0;
this.okButton.Text = "OK";
this.okButton.UseVisualStyleBackColor = true;
this.okButton.Click += new System.EventHandler(this.OkButton_Click);
this.Controls.Add(this.okButton);

// Cancel Button
this.cancelButton.Location = new System.Drawing.Point(185, 230); // Position
this.cancelButton.Name = "cancelButton";
this.cancelButton.Size = new System.Drawing.Size(75, 23); // Set size
this.cancelButton.TabIndex = 0;
this.cancelButton.Text = "Cancel";
this.cancelButton.UseVisualStyleBackColor = true;
this.cancelButton.Click += new System.EventHandler(this.CancelButton_Click);
this.Controls.Add(this.cancelButton);
}

private void CircularBorderForm_Paint(object sender, PaintEventArgs e)
{
// Create a circular region
GraphicsPath path = new GraphicsPath();
path.AddEllipse(0, 0, this.Width - 1, this.Height - 1);
Region = new Region(path);

// Dispose the GraphicsPath to free resources
path.Dispose();
}

private void Form_MouseDown(object sender, MouseEventArgs e)
{
lastLocation = e.Location;
}

private void Form_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
this.Left += e.X - lastLocation.X;
this.Top += e.Y - lastLocation.Y;
}
}

private void Form_MouseUp(object sender, MouseEventArgs e)
{
lastLocation = System.Drawing.Point.Empty;
}
private void OkButton_Click(object sender, EventArgs e)
{
SelectedDraftingViews = new List<ViewDrafting>(); // Initialize the list
string selectedSheetName = sheetComboBox.SelectedItem as string;

try
{
List<string> selectedDraftingViewNames = new List<string>();

if (!string.IsNullOrEmpty(selectedSheetName) && draftingViewListBox != null)
{
// Get the selected drafting views
foreach (var selectedItem in draftingViewListBox.SelectedItems)
{
if (selectedItem != null && !string.IsNullOrEmpty(selectedItem.ToString()))
{
if (importDraftingViewsFromExternalDoc != null)
{
var draftingView = importDraftingViewsFromExternalDoc.FirstOrDefault(x => x.Name == selectedItem.ToString());
if (draftingView != null)
{
SelectedDraftingViews.Add(importDraftingViewsFromExternalDoc.FirstOrDefault(x => x.Name == selectedItem.ToString()));
}
}
else
{
TaskDialog.Show("Error", "importDraftingViewsFromExternalDoc is null");
}
}
}

SelectedSheet = sheets.FirstOrDefault(sheet =>
sheet.Name?.Trim().Equals(selectedSheetName?.Trim(), StringComparison.OrdinalIgnoreCase) == true);

if (SelectedSheet == null)
{
TaskDialog.Show("Error", $"Selected sheet '{selectedSheetName}' not found.");
return;
}

this.DialogResult = DialogResult.OK;
this.Close();
}
}
catch (NullReferenceException nullEx)
{
TaskDialog.Show("Error", "A null reference exception occurred. Details: " + nullEx.Message);
}
catch (Exception ex)
{
TaskDialog.Show("Error", $"(21){ex.Message}");
}
}

private void listBox_KeyDown(object sender, KeyEventArgs e)
{
// Check if Ctrl+A is pressed
if (e.Control && e.KeyCode == Keys.A)
{
// Select all items
for (int i = 0; i < draftingViewListBox.Items.Count; i++)
{
draftingViewListBox.SetSelected(i, true);
}
}
else if (e.KeyCode == Keys.Escape) // Check if Escape key is pressed
{
// Deselect all items
draftingViewListBox.ClearSelected();
}
}

private void CancelButton_Click(object sender, EventArgs e)
{
DialogResult = DialogResult.Cancel;
Close();
}
}

[ed_sa]

This is the portion Im referring to. blockId is not null but viewport is:

}

// Create a viewport for the duplicated drafting view
Viewport viewport = Viewport.Create(currentDoc, selectedSheet.Id, blockId, XYZ.Zero);
if (viewport == null)
{