DoCmd.TransferText error 3051 - ms-access

Question

I am attempting to import data into my MS Access project via TransferText, but am receiving error #3051: "The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permissions to view and write its data."
It is odd to me that the filename given in the error message is blank. I have checked and rechecked the file name, even to perform a check "If Not fso.FileExists(file_name) Then ... End If" prior to the TransferText call.
I have also checked and rechecked the table name and the file permissions. The table is successfully emptied before the TransferText call, so I know that works. The file is in a subfolder relative to the Access database file in a folder on my desktop. I have not set or unset any permissions for any of the folders or files.
Until now I had been using DoCmd.TransferSpreadsheet to import the data that is downloaded from a web based tool, but I found Excel was misinterpreting some alphanumeric codes as numbers in scientific format, such as 1E100 would become 1E+100 in the Excel file, so the data was corrupted before getting to the Access database. These codes are getting corrupted in uncorrectable ways, so I can't modify the data after import. I found I could save the data from the web tool as a CSV file rather than an Excel file; this led me to try to use DoCmd.TransferText.
Below is the code I am using:
Private Function ImportExcel( _
ByVal file_name As String, _
ByVal table_name As String _
) As Integer
On Error GoTo Error
Dim fso As FileSystemObject, folder_name As String
Dim xl_book As Excel.Workbook
Dim xl_sheet As Excel.Worksheet
Dim i As Integer
' suppress excel's file-not-found popup
Set fso = New FileSystemObject
If Not fso.FileExists(file_name) Then
ImportExcel = -1
GoTo Finish
End If
' gets a workbook from a global application object
Set xl_book = Util.GetExcelWorkbook( _
file_name:=file_name, _
visible:=False, _
use_cache:=True _
)
If xl_book Is Nothing Then
ImportExcel = -1
GoTo Finish
End If
' always use the first worksheet
Set xl_sheet = xl_book.Sheets(1)
' fake the first record to force columns types
xl_sheet.range("A2").EntireRow.Insert
For i = 1 To xl_sheet.UsedRange.columns.count
xl_sheet.Cells(2, i) = "test"
Next i
' make sure the table is closed
DoCmd.Close _
ObjectType:=acTable, _
ObjectName:=table_name, _
Save:=acSaveNo
' link to file
DoCmd.SetWarnings False
If ".csv" = Right(file_name, 4) Then
' empty table
DoCmd.RunSQL "DELETE * FROM " & table_name, True
' import data
Debug.Print table_name
Debug.Print file_name
DoCmd.TransferText _
TransferType:=acImportDelim, _
SpecificationName:=table_name & " Import Spec", _
TableName:=table_name, _
FileName:=file_name, _
HasFieldNames:=True
Else
' delete table
On Error Resume Next
DoCmd.DeleteObject _
ObjectType:=acTable, _
ObjectName:=table_name
If 0 <> Err.Number Then
Resume Next
End If
On Error GoTo Error
' import data
DoCmd.TransferSpreadsheet _
TransferType:=acImport, _
TableName:=table_name, _
FileName:=file_name, _
HasFieldNames:=True, _
range:=xl_sheet.NAME() & "!" & _
xl_sheet.range( _
xl_sheet.Cells(1, 1), _
xl_sheet.Cells( _
xl_sheet.UsedRange.rows.count, _
xl_sheet.UsedRange.columns.count _
) _
).Address(RowAbsolute:=False, ColumnAbsolute:=False), _
SpreadsheetType:=acSpreadsheetTypeExcel9
End If
DoCmd.SetWarnings True
Finish:
Set xl_sheet = Nothing
If Not xl_book Is Nothing Then
xl_book.Close SaveChanges:=False
End If
Set xl_book = Nothing
Set fso = Nothing
Exit Function
Error:
Resume Finish
End Function
The two Debug.Print calls just prior to the DoCmd.TransferText call print exactly what is expected.