Downloading simple text/csv file in Chrome fails - asp.net

Question

I'm trying to figure out a problem that we're facing with the download and the problem seems to exist only in Chrome and only for txt and csv files. Downloading zip files works just as expected. IE and Firefox works for all scenarios.
For some reason Chrome downloads both txt and csv files without properly setting the name. Files inherit the name of the page which they were downloaded from, and don't have an extension ().
I have a simple Webform with just 3 linkbuttons a fairly straightforward code behind, which I simplified for the sake of this question.
Imports System.IO
Public Class _Default
Inherits Page
Private Const FILE_PATH_CSV As String = "D:\Temp\Download\testFile.csv"
Private Const FILE_PATH_ZIP As String = "D:\Temp\Download\testFile.zip"
Private Const FILE_PATH_TXT As String = "D:\Temp\Download\testFile.txt"
Private Sub btnDownloadCSV_Click(sender As Object, e As EventArgs) Handles btnDownloadCSV.Click
Dim file As New FileInfo(FILE_PATH_CSV)
If Not file.Exists() Then
Throw New Exception("No file")
End If
Try
DownloadFile(file)
Catch ex As Exception
'TODO: Log!
End Try
End Sub
Private Sub btnDownloadTXT_Click(sender As Object, e As EventArgs) Handles btnDownloadTXT.Click
Dim file As New FileInfo(FILE_PATH_TXT)
If Not file.Exists() Then
Throw New Exception("No file")
End If
Try
DownloadFile(file)
Catch ex As Exception
'TODO: Log!
End Try
End Sub
Private Sub btnDownloadZIP_Click(sender As Object, e As EventArgs) Handles btnDownloadZIP.Click
Dim file As New FileInfo(FILE_PATH_ZIP)
If Not file.Exists() Then
Throw New Exception("No file")
End If
Try
DownloadFile(file)
Catch ex As Exception
'TODO: Log!
Finally
With Response
.Flush()
.End()
End With
End Try
End Sub
Private Sub DownloadFile(ByVal file As FileInfo)
With Response
.Clear()
.ClearHeaders()
.ClearContent()
.Buffer = True
Response.ContentType = GetContentType(file)
Response.AddHeader("Content-Disposition:", String.Format("attachment;filename=""{0}""", file.Name.ToString()))
Response.AddHeader("Content-Length", file.Length.ToString())
Response.TransmitFile(file.FullName)
End With
End Sub
Private Function GetContentType(ByVal file As FileInfo)
Select Case file.Extension.ToLower()
Case ".txt", ".csv"
Return "application/octet-stream"
Case ".zip"
Return "application/x-zip-compressed"
Case Else
Return "application/octet-stream"
End Select
End Function
End Class
I've tried switching the content type to 'text/plain' or other options as I searched the web for the answer but had no luck. I feel like I'm missing something, but I can't find anything that answers my question online.
Does anyone have any ideas why this might be happening?
Any help is appreciated.

Answer 1

You need to change your MIME types to the correct values.
Case ".csv"
Return "text/csv"
Case ".txt"
Return "text/plain"
You may also need to change the method of sending the file from
Response.TransmitFile(file.FullName)
to
Response.WriteFile(file.FullName, False)
The documentation on MSDN isn't clear about what the differences are between the two methods. I have never used TransmitFile, but have used WriteFile successfully.

Answer 2

Problem solved. I guess I should be more careful with copy/paste as that caused me 2 days of very frustrated debugging.
Response.AddHeader("Content-Disposition:", String.Format("attachment;filename=""{0}""", file.Name.ToString()))
Should be
Response.AddHeader("Content-Disposition", String.Format("attachment;filename=""{0}""", file.Name.ToString()))
Extra colon in there was not necessary and when I removed it - everything worked!
Thanks to all who helped!