UG documentation 995570: Saving Excel file causes SystemUnauthorizedAccessException

Document-Processing/Excel/Excel-Library/NET/faqs/how-to-overcome-unauthorizedaccessexception-for-hidden-excel-file.md

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+---
+title: How to avoid UnauthorizedAccessException using xlsio? | Syncfusion
+description: This page explains how to overcome UnauthorizedAccessException when saving hidden Excel files programmatically using Syncfusion XlsIO and FileAttributes.
+platform: document-processing
+control: XlsIO
+documentation: UG
+---
+
+# How to avoid UnauthorizedAccessException using xlsio?
+
+When saving an Excel file that has the hidden attribute set, an `UnauthorizedAccessException` may occur because the file is protected by the operating system's file attributes. To overcome this exception, you can temporarily change the hidden state of the file to normal, perform the save operation, and then restore the hidden attribute back using the `FileAttributes` enumeration.
+
+The following code example demonstrates how to toggle the hidden file attribute before opening and after saving the workbook.
+
+{% tabs %}
+{% highlight c# tabtitle="C# [Cross-platform]" %}
+using (ExcelEngine excelEngine = new ExcelEngine())
+{
+    //Set the default version as Excel 2016
+    excelEngine.Excel.DefaultVersion = ExcelVersion.Excel2016;
+
+    File.SetAttributes(Path.GetFullPath("Data/InputTemplate.xlsm"), FileAttributes.Normal);
+
+    //Open a workbook
+    IWorkbook workbook = excelEngine.Excel.Workbooks.Open(Path.GetFullPath("Data/InputTemplate.xlsm"));
+
+    IWorksheet worksheet = workbook.Worksheets[0];
+
+    worksheet.Range["A2"].Text = "Hello, World!";
+
+    File.SetAttributes(Path.GetFullPath("Data/InputTemplate.xlsm"), FileAttributes.Hidden);
+
+    //Save the workbook to disk in xlsx format
+    workbook.SaveAs(Path.GetFullPath("Output/Output.xlsm"));
+}
+{% endhighlight %}
+
+{% highlight c# tabtitle="C# [Windows-specific]" %}
+using (ExcelEngine excelEngine = new ExcelEngine())
+{
+    //Set the default version as Excel 2016
+    excelEngine.Excel.DefaultVersion = ExcelVersion.Excel2016;
+
+    File.SetAttributes("InputTemplate.xlsm", FileAttributes.Normal);
+
+    //Open a workbook
+    IWorkbook workbook = excelEngine.Excel.Workbooks.Open("InputTemplate.xlsm");
+
+    IWorksheet worksheet = workbook.Worksheets[0];
+
+    worksheet.Range["A2"].Text = "Hello, World!";
+
+    File.SetAttributes("InputTemplate.xlsm", FileAttributes.Hidden);
+
+    //Save the workbook to disk in xlsx format
+    workbook.SaveAs("Output.xlsm");
+}
+{% endhighlight %}
+
+{% highlight vb.net tabtitle="VB.NET [Windows-specific]" %}
+Using excelEngine As New ExcelEngine()
+    'Set the default version as Excel 2016
+    excelEngine.Excel.DefaultVersion = ExcelVersion.Excel2016
+
+    File.SetAttributes("InputTemplate.xlsm", FileAttributes.Normal)
+
+    'Open a workbook
+    Dim workbook As IWorkbook = excelEngine.Excel.Workbooks.Open("InputTemplate.xlsm")
+
+    Dim worksheet As IWorksheet = workbook.Worksheets(0)
+
+    worksheet.Range("A2").Text = "Hello, World!"
+
+    File.SetAttributes("InputTemplate.xlsm", FileAttributes.Hidden)
+
+    'Save the workbook to disk in xlsx format
+    workbook.SaveAs("Output.xlsm")
+End Using
+{% endhighlight %}
+{% endtabs %}
+
+## See Also
+
+* [How to overcome UnauthorizedAccessException?](https://help.syncfusion.com/document-processing/excel/excel-library/net/faqs/how-to-overcome-unauthorizedaccessexception)
+* [How to overcome StackOverflow exception with IWorksheet Calculate()?](https://help.syncfusion.com/document-processing/excel/excel-library/net/faqs/how-to-overcome-stackoverflow-exception-with-iworksheet-calculate)
+* [How to avoid exception when adding worksheets with same name?](https://help.syncfusion.com/document-processing/excel/excel-library/net/faqs/how-to-avoid-exception-when-adding-worksheets-with-same-name)