InsertPdf後出現AccessViolationException，附HTML頁首/頁尾

Updated: 2026年6月12日

在使用InsertPdf合併來自另一個文件的頁面後，對PdfDocument呼叫AddHtmlHeaders時會拋出AccessViolationException。在Debug構建中或附加除錯器時，該例外狀況不會發生。

System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
   at IronPdf.PdfDocument.AddHtmlHeaders(...)

System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
   at IronPdf.PdfDocument.AddHtmlHeaders(...)

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在Release構建中，.NET JIT優化器允許垃圾回收器在管理程式碼能證明物件不會被再次引用後，在其詞彙範疇結束之前回收管理物件。傳遞給InsertPdf的PdfDocument可以在IronPDF的原生Chrome層仍在讀取時被回收。隨後的AddHtmlHeaders呼叫然後存取已釋放的記憶體，導致存取衝突。

解決方案

選擇1：在InsertPdf之前應用頁首和頁尾（推薦）

重新排列操作順序，使頁首和頁尾在插入任何頁面之前寫入到基本文件中：

var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
{
    HtmlFragment = "<div style='text-align:right; font-size:10px'>Page {page} of {total-pages}</div>"
};

var basePdf = renderer.RenderHtmlAsPdf(baseHtml);

basePdf.AddHtmlHeaders(renderer.RenderingOptions.HtmlHeader);

var supplementPdf = PdfDocument.FromFile("supplement.pdf");
basePdf.InsertPdf(supplementPdf, 0);

basePdf.SaveAs("output.pdf");

var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
{
    HtmlFragment = "<div style='text-align:right; font-size:10px'>Page {page} of {total-pages}</div>"
};

var basePdf = renderer.RenderHtmlAsPdf(baseHtml);

basePdf.AddHtmlHeaders(renderer.RenderingOptions.HtmlHeader);

var supplementPdf = PdfDocument.FromFile("supplement.pdf");
basePdf.InsertPdf(supplementPdf, 0);

basePdf.SaveAs("output.pdf");

選擇2：使用GC.KeepAlive防止過早回收

如果無法改變操作順序，則將來源PdfDocument的受管理生命週期延長至AddHtmlHeaders呼叫之後：

var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
{
    HtmlFragment = "<div style='text-align:right; font-size:10px'>Page {page} of {total-pages}</div>"
};

var basePdf = renderer.RenderHtmlAsPdf(baseHtml);
var supplementPdf = PdfDocument.FromFile("supplement.pdf");

basePdf.InsertPdf(supplementPdf, 0);
basePdf.AddHtmlHeaders(renderer.RenderingOptions.HtmlHeader);

GC.KeepAlive(supplementPdf);

basePdf.SaveAs("output.pdf");

var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
{
    HtmlFragment = "<div style='text-align:right; font-size:10px'>Page {page} of {total-pages}</div>"
};

var basePdf = renderer.RenderHtmlAsPdf(baseHtml);
var supplementPdf = PdfDocument.FromFile("supplement.pdf");

basePdf.InsertPdf(supplementPdf, 0);
basePdf.AddHtmlHeaders(renderer.RenderingOptions.HtmlHeader);

GC.KeepAlive(supplementPdf);

basePdf.SaveAs("output.pdf");

放置在AddHtmlHeaders之後的GC.KeepAlive(supplementPdf)可防止JIT在原生合併完成前排程回收supplementPdf。