Cannot Access a Closed Stream Error in iTextSharp (Issue Fixed)

When generating PDF documents with iTextSharp and using MemoryStream, developers frequently encounter the ObjectDisposedException: Cannot access a closed Stream error. With over 58,000 views on Stack Overflow discussions of this issue, it remains one of the most common problems when working with iTextSharp's stream handling. The error occurs because iTextSharp automatically disposes the underlying stream when the Document is closed, catching developers off guard when they attempt to use the stream afterward.

The Problem

The ObjectDisposedException appears when code attempts to access a MemoryStream after iTextSharp has already closed it. This typically happens when developers expect to use the stream's contents after calling document.Close() or when the Document object is disposed via a using statement.

The core issue stems from iTextSharp's RAII (Resource Acquisition Is Initialization) pattern: when you pass a stream to PdfWriter.GetInstance(), iTextSharp takes ownership of that stream's lifecycle. When the Document closes, it closes all associated resources, including the stream you provided.

This behavior is counterintuitive because developers often expect to:

1. Create a MemoryStream
2. Generate PDF content
3. Close the document
4. Use the stream to return data, save to disk, or send as an email attachment

Step 4 fails because the stream no longer exists.

Error Messages and Symptoms

The exception typically appears with this stack trace:

System.ObjectDisposedException: Cannot access a closed Stream.
   at System.IO.MemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count)
   at iTextSharp.text.pdf.PdfWriter.Close()
   at iTextSharp.text.Document.Close()

Or when attempting to read after close:

System.ObjectDisposedException: Cannot access a closed Stream.
   at System.IO.MemoryStream.get_Position()

The exception occurs at different points depending on the code structure:

• During document.Close() if nested incorrectly
• When accessing memoryStream.Position after close
• When calling memoryStream.ToArray() in certain patterns
• When passing the stream to a FileResult in ASP.NET

Who Is Affected

This issue impacts any .NET application using iTextSharp or iText 7 with in-memory PDF generation:

Framework Versions: .NET Framework 4.x, .NET Core 2.1+, .NET 5/6/7/8

Common Scenarios:

• Web applications returning PDFs to browsers via MVC/WebAPI
• Email attachments generated dynamically
• PDF merge operations using MemoryStream as intermediate storage
• Batch processing where PDFs are held in memory before saving
• Unit tests validating PDF generation

Operations That Trigger It:

• Any use of using statements around MemoryStream with iTextSharp
• Calling stream.Position = 0 after document close
• Passing MemoryStream to FileResult in ASP.NET
• Attempting to read stream bytes after document finalization

Evidence from the Developer Community

Scale of the Problem

Metric	Value
Stack Overflow Views	58,000+
Question Upvotes	12
Years Discussed	2010-2024
Related Questions	50+

Community Reports

"Stack trace looks like [ObjectDisposedException: Cannot access a closed Stream"
— Developer, Stack Overflow, March 2016

"I get a ObjectDisposedException with the message 'Cannot access a closed Stream.' The exception is thrown at the line outputStream.Position = 0"
— Developer, Microsoft Q&A Forums

"From the error, you can know that the Stream you are preparing to operate has been disabled. This is because iTextSharp has automatically disabled the generated Stream."
— Alibaba Cloud Developer Community

The problem persists across iTextSharp versions because it is a deliberate design decision rather than a bug. The library follows the pattern of taking ownership of streams passed to it.

Root Cause Analysis

The fundamental cause is iTextSharp's stream ownership model. When you call PdfWriter.GetInstance(document, stream), the PdfWriter becomes the owner of that stream. When document.Close() executes, it cascades through:

1. Document.Close() calls PdfWriter.Close()
2. PdfWriter.Close() flushes all pending content
3. PdfWriter.Close() then closes the underlying stream

This is the RAII pattern in action. Since you gave a lifetime-managed object to Document, it is responsible for cleaning it up.

Consider this common (broken) pattern:

// BROKEN CODE - causes ObjectDisposedException
public byte[] GeneratePdf()
{
    using (var ms = new MemoryStream())
    {
        var document = new Document();
        PdfWriter.GetInstance(document, ms);

        document.Open();
        document.Add(new Paragraph("Hello World"));
        document.Close();  // This closes the MemoryStream!

        ms.Position = 0;   // EXCEPTION: Cannot access a closed Stream
        return ms.ToArray();
    }
}

The problem is that document.Close() internally closes the MemoryStream. When the code then tries to reset the position or read bytes, the stream is already disposed.

Attempted Workarounds

The iTextSharp community has developed several workarounds over the years.

Workaround 1: Set CloseStream to False

Approach: Configure PdfWriter to not close the underlying stream when the document closes.

public byte[] GeneratePdf()
{
    using (var ms = new MemoryStream())
    {
        var document = new Document();
        var writer = PdfWriter.GetInstance(document, ms);

        document.Open();
        document.Add(new Paragraph("Hello World"));

        // Prevent stream closure
        writer.CloseStream = false;

        document.Close();

        ms.Position = 0;
        return ms.ToArray();
    }
}

Limitations:

• Requires remembering to set the property before every close
• Easy to forget, especially in complex code paths
• Property must be set before document.Close(), not after
• Not immediately obvious from the API that this is needed

Workaround 2: Use ToArray() Immediately After Close

Approach: Exploit the fact that MemoryStream.ToArray() works even after the stream is disposed.

public byte[] GeneratePdf()
{
    var ms = new MemoryStream();
    var document = new Document();
    PdfWriter.GetInstance(document, ms);

    document.Open();
    document.Add(new Paragraph("Hello World"));
    document.Close();  // Stream is now closed

    // ToArray() still works on disposed MemoryStream
    return ms.ToArray();
}

Limitations:

• Only works for ToArray() - cannot use the stream for anything else
• Unintuitive - accessing a disposed object goes against .NET conventions
• Requires removing the using statement, which feels wrong
• Cannot stream directly to response or file

Workaround 3: Create a New Stream from the Byte Array

Approach: Extract the byte array and create a new MemoryStream.

public MemoryStream GeneratePdf()
{
    MemoryStream ms = new MemoryStream();
    var document = new Document();
    PdfWriter.GetInstance(document, ms);

    document.Open();
    document.Add(new Paragraph("Hello World"));
    document.Close();

    // Create new stream from the closed one's data
    return new MemoryStream(ms.ToArray());
}

Limitations:

• Creates an unnecessary copy of the data
• Memory overhead doubles during the copy
• Additional complexity for what should be simple
• Caller must now dispose the returned stream

A Different Approach: IronPDF

IronPDF handles memory management differently, avoiding the stream ownership issues that plague iTextSharp development. Rather than taking ownership of streams passed to it, IronPDF provides direct access to the generated PDF's binary data through a property.

Why IronPDF Avoids This Problem

IronPDF's architecture separates PDF generation from output handling:

1. Generation Phase: The ChromePdfRenderer creates a PdfDocument object
2. Output Phase: You choose how to output - file, byte array, or stream
3. No Implicit Disposal: The PdfDocument owns its data; you control the output lifecycle

The BinaryData property returns a byte[] directly - no stream position management, no disposal timing issues, no ownership transfer problems.

Code Example

using IronPdf;

public class PdfService
{
    // Simple byte array output - no stream issues possible
    public byte[] GeneratePdf()
    {
        var renderer = new ChromePdfRenderer();

        string html = @"
<!DOCTYPE html>
<html>
<head>
    <style>
        body { font-family: 'Segoe UI', Arial, sans-serif; padding: 40px; }
        h1 { color: #2c3e50; }
    </style>
</head>
<body>
    <h1>Hello World</h1>
    <p>Generated without stream disposal concerns.</p>
</body>
</html>";

        using var pdf = renderer.RenderHtmlAsPdf(html);

        // BinaryData is a byte[] - no stream to close
        return pdf.BinaryData;
    }

    // ASP.NET MVC - return PDF to browser
    public FileContentResult GetPdfForBrowser()
    {
        var renderer = new ChromePdfRenderer();

        using var pdf = renderer.RenderHtmlAsPdf("<h1>Report</h1>");

        // No stream position reset needed
        // No ObjectDisposedException possible
        return new FileContentResult(pdf.BinaryData, "application/pdf")
        {
            FileDownloadName = "report.pdf"
        };
    }

    // Email attachment scenario
    public void SendPdfByEmail(string recipient)
    {
        var renderer = new ChromePdfRenderer();

        using var pdf = renderer.RenderHtmlAsPdf("<h1>Invoice</h1>");

        var attachment = new Attachment(
            new MemoryStream(pdf.BinaryData),  // Create stream from bytes
            "invoice.pdf",
            "application/pdf"
        );

        // Stream created here is fully under your control
        using var message = new MailMessage("[e-mail]", recipient)
        {
            Subject = "Your Invoice",
            Attachments = { attachment }
        };

        using var client = new SmtpClient("smtp.example.com");
        client.Send(message);
    }

    // Save to file - also straightforward
    public void SaveToFile(string path)
    {
        var renderer = new ChromePdfRenderer();

        using var pdf = renderer.RenderHtmlAsPdf("<h1>Document</h1>");

        // SaveAs handles file I/O internally
        pdf.SaveAs(path);
    }
}

Key points about this code:

• pdf.BinaryData returns byte[] directly - no stream lifecycle to manage
• You create any streams you need - you own them, you dispose them
• The using statement on PdfDocument disposes the PDF object itself, not any external streams
• Same pattern works for web responses, email attachments, file saves, and database storage

API Reference

For more details on the methods used:

• ChromePdfRenderer
• PdfDocument.BinaryData
• Rendering HTML to PDF

Migration Considerations

Licensing

• IronPDF is commercial software with perpetual licensing options
• Free trial available for evaluation
• Licensing information

API Differences

iTextSharp	IronPDF
Document + PdfWriter + Stream	ChromePdfRenderer + PdfDocument
Object-based document construction	HTML/CSS-based rendering
Stream passed in, ownership transferred	Byte array output, no ownership transfer
Must remember CloseStream = false	No equivalent concern

What You Gain

• No stream disposal timing bugs
• No ObjectDisposedException from closed streams
• Direct byte array access without workarounds
• Simpler code with fewer failure modes

What to Consider

• Different approach: HTML/CSS rendering vs. programmatic document building
• Commercial licensing required for production use
• Chrome-based rendering adds dependencies

Conclusion

The "Cannot access a closed Stream" error in iTextSharp stems from the library's decision to take ownership of streams passed to it. While workarounds exist (setting CloseStream = false or using ToArray() after close), they require remembering specific patterns and are easy to get wrong. IronPDF's approach of providing direct byte array access through the BinaryData property eliminates this entire category of stream lifecycle bugs.

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Jacob Mellor built IronPDF and has spent 25+ years developing commercial software tools.

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References

1. Stack Overflow: Cannot access a closed Stream{:rel="nofollow"} - 58K+ views
2. Alibaba Cloud: Solution to Cannot access a closed Stream in iTextSharp{:rel="nofollow"} - Detailed explanation
3. PdfReport.Core Issue #39: Getting "Closed stream" error{:rel="nofollow"} - GitHub discussion
4. Microsoft Q&A: Memory stream to file error{:rel="nofollow"} - Related stream issues

For the latest IronPDF documentation and tutorials, visit ironpdf.com.