A method in dumping a GridView to an Excel file to download/open from the internet was recently broken with new Windows Updates.
My code dumps from a GridView to an XLS file using StringWriter, HTMLTextWriter and RenderControl. A common approach using the following code from http://www.aspsnippets.com/Articles/Export-GridView-to-Excel-in-ASPNet-with-Formatting-using-C-and-VBNet.aspx
Protected Sub ExportToExcel(sender As Object, e As EventArgs)
Response.Clear()
Response.Buffer = True
Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.xls")
Response.Charset = ""
Response.ContentType = "application/vnd.ms-excel"
Using sw As New StringWriter()
Dim hw As New HtmlTextWriter(sw)
'To Export all pages
GridView1.AllowPaging = False
Me.BindGrid()
GridView1.HeaderRow.BackColor = Color.White
For Each cell As TableCell In GridView1.HeaderRow.Cells
cell.BackColor = GridView1.HeaderStyle.BackColor
Next
For Each row As GridViewRow In GridView1.Rows
row.BackColor = Color.White
For Each cell As TableCell In row.Cells
If row.RowIndex Mod 2 = 0 Then
cell.BackColor = GridView1.AlternatingRowStyle.BackColor
Else
cell.BackColor = GridView1.RowStyle.BackColor
End If
cell.CssClass = "textmode"
Next
Next
GridView1.RenderControl(hw)
'style to format numbers to string
Dim style As String = "<style> .textmode { } </style>"
Response.Write(style)
Response.Output.Write(sw.ToString())
Response.Flush()
Response.[End]()
End Using
End Sub
Public Overrides Sub VerifyRenderingInServerForm(control As Control)
' Verifies that the control is rendered
End Sub
Excel (2013) will open to a blank window, with no warning or message as to why anything was blocked, and without option to accept the file to open.
My code is run on an intranet site, and I do have access to group policies / settings / user configurations in Windows.
Solution 1
1) Open Excel Go to File Options
2) Click Trust Center -> Trust Center Settings
3) Go to Protected View. there are 3 options that show that were all clicked. Uncheck the first option that reads -- "Enable Protected View for files originating from the Internet". In some cases as reported in the comments below both the 1st and 2nd options need to be unchecked (Thanks @mosheb)
Solution 2
Uninstall these Windows Updates: