System.InvalidOperationException: 'Operation is not valid due to the current state of the object.' on a update query in vb.net - vb.net

Question

Hello I am trying to do an update query on my database however I end up with this error message
System.InvalidOperationException: 'Operation is not valid due to the current state of the object.'
Here is the code for my search query which I then use in the update
Private Function SearchData(Fname As String, ID As Int32) As DataTable
Dim dt As New DataTable
Dim ds As New DataSet
Dim ssql As String = "SELECT * FROM customers WHERE fname LIKE #Fname OR CustomerID = #ID"
Using con As New SQLiteConnection(ConStr),
cmd As New SQLiteCommand(ssql, con)
con.Open()
cmd.Parameters.Add("#Fname", DbType.String).Value = $"%{Fname}%"
cmd.Parameters.Add("#ID", DbType.Int32).Value = ID
dt.Load(cmd.ExecuteReader)
Dim da As New SQLiteDataAdapter(cmd)
da.Fill(ds, "customers")
dt = ds.Tables(0)
If dt.Rows.Count > 0 Then
ToTextbox(dt)
End If
End Using
Return dt
End Function
This is the ToTextBox function
Public Sub ToTextbox(ByVal newdt)
txtFName.Text = newdt.Rows(0)(1).ToString()
txtLName.Text = newdt.Rows(0)(2).ToString()
mtxtContactNumber.Text = newdt.rows(0)(3).ToString()
txtAddress.Text = newdt.rows(0)(4).ToString()
txtTown.Text = newdt.rows(0)(5).ToString()
txtPostCode.Text = newdt.rows(0)(6).ToString()
End Sub
And the update function
Public Function updateguest(FirstName As String, ID As Integer) As Integer
Dim Result As Integer
Dim usql As String = "UPDATE Customers SET fname = #fname WHERE CustomerID = #ID;"
Using con As New SQLiteConnection(ConStr),
cmd As New SQLiteCommand(usql, con)
con.Open()
cmd.Parameters.Add("#fname", DbType.String).Value = FirstName
cmd.Parameters.Add("#ID", DbType.Int32).Value = ID
con.Open()
Result = cmd.ExecuteNonQuery
con.Close()
End Using
Return Result
End Function
And the Update button
Private Sub IbtnUpdate_Click(sender As Object, e As EventArgs) Handles ibtnUpdate.Click
Try
Dim Result = updateguest(txtFName.Text, CInt(txtSearchID.Text))
If Result > 0 Then
MsgBox("New RECORD HAS BEEN UPDATED!")
Else
MsgBox("NO RECORD HAS BEEN UPDATDD!")
End If
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub

Answer 1

I believe you update problems are solved in comments.
You still have too much stuff in your DataAccess code. Just return the DataTable and use it in the user interface code.
Private Function SearchData(Fname As String, ID As Int32) As DataTable
Dim dt As New DataTable
Dim ssql As String = "SELECT * FROM customers WHERE fname LIKE #Fname OR CustomerID = #ID"
Using con As New SQLiteConnection(ConStr),
cmd As New SQLiteCommand(ssql, con)
con.Open()
cmd.Parameters.Add("#Fname", DbType.String).Value = $"%{Fname}%"
cmd.Parameters.Add("#ID", DbType.Int32).Value = ID
dt.Load(cmd.ExecuteReader)
End Using
Return dt
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim dt = SearchData(FirstNameTextBox.Text, CInt(IDTextBox.Text))
If dt.Rows.Count > 0 Then
ToTextbox(dt)
End If
End Sub
Public Sub ToTextbox(ByVal newdt As DataTable)
txtFName.Text = newdt.Rows(0)(1).ToString()
txtLName.Text = newdt.Rows(0)(2).ToString()
mtxtContactNumber.Text = newdt.Rows(0)(3).ToString()
txtAddress.Text = newdt.Rows(0)(4).ToString()
txtTown.Text = newdt.Rows(0)(5).ToString()
txtPostCode.Text = newdt.Rows(0)(6).ToString()
End Sub