I am using VB

Problem: when i click on sort col and click on refresh button, than i get popup browers message "To display the webpage again, the web brower need to resend the infomation you've previously submitted."

Recreate this problem: click on sorting col of gridview -> refresh page

I think its causing this issue bc of two post requests. first post request when I sort on page and 2nd post request when I refresh. I know the issue but I don't know how to fix this.

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" DataKeyNames="ID" 
            AllowSorting="True"  OnSorting="GridView1_Sorting" AllowPaging="true" PageSize="9" OnPageIndexChanging="GridView1_PageIndexChanging">
            ...
            <asp:HyperLink ID="lnkView" runat="server" Visible="true" NavigateUrl='<%# Eval("ID", "View.aspx?ID={0}") %>' OnClick="window.open(this.href,'targetWindow','width=1000,height=1000,scrollbars=1,resizable=1'); return false;">View</asp:HyperLink>
            ...
            <asp:HyperLink ID="lnkEdit" runat="server" Visible="true" NavigateUrl='<%# Eval("ID", "Edit.aspx?ID={0}") %>' OnClick="window.open(this.href,'targetWindow','width=1000,height=1000,scrollbars=1,resizable=1'); return false;">Edit</asp:HyperLink>
            ...

back end method

'golbal variable
Dim sortField As String

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
       If Not IsPostBack Then
        Dim da As SqlDataAdapter
        Dim ds As DataSet = New DataSet()
        Dim dt As DataTable = New DataTable
        Dim sqlConn As New SqlConnection(myConnectionString)
        Dim query1 As String = "SELECT * FROM [mytable] ORDER BY Created_dt DESC;"

        Try
            sqlConn.Open()

            Dim cmd = New SqlCommand(query1, sqlConn)
            da = New SqlDataAdapter(cmd)
            Dim builder As SqlCommandBuilder = New SqlCommandBuilder(da)
            da.Fill(ds, "mytable")
            Dim a As Integer = ds.Tables("mytable").Rows.Count
            If a = 0 Then
                ErrorMessage.Text = "0 results found."
            End If

            da.Fill(dt)
            ViewState("SaveData") = dt
            GridView1.DataSource = ViewState("SaveData")
            GridView1.DataBind()

            sqlConn.Close()
        Catch ex As Exception
            ErrorMessage.Text = "error"
        End Try
       End If
   End Sub

back end method

   Protected Sub GridView1_Sorting(ByVal sender As Object, ByVal e As GridViewSortEventArgs)
       'Retrieve the data source from session state.
       Dim dt As DataTable = CType(ViewState("SaveData"), DataTable)

       sortField = e.SortExp<b></b>ression
       If Trim(ViewState("sortMode")) <> "" Then
           If ViewState("sortMode").ToString().Trim().Equals("ASC") Then
               ViewState("sortMode") = "DESC"
           Else
               ViewState("sortMode") = "ASC"
           End If
       Else
           ViewState("sortMode") = "ASC"
       End If
       'txtSortMode.Text = sortMode

       Dim dv As New DataView(dt)
       dv.Sort = sortField.Trim() & " " & ViewState("sortMode")
       GridView1.DataSource = dv
       GridView1.DataBind()
   End Sub

I just noticed this warning only shows in IE... it work fine in google chrome.

I think its causing this issue bc of two post requests. first post request when I sort on page and 2nd post request when I refresh. I know the issue but I don't know how to fix this.

aw this is also i was thinking. Looks like post-redirect-get is the solution but how can I do thjis with what I am trying to do? any ideas?

look like I need to find a javascript which redirect post request to GET request... on page refresh.

My first thought is why 2 refreshes? In the first code block with <asp:GridView lines 4 and 6 look like a duplicate. I could be wrong but maybe only one is required?

line 4 is view button and line 6 is edit button. i dont see the 2 refreshes? clicking on them will open different vb class

Then I'm left with the feeling there's unpublished code here. You shared some of the code but this looks incomplete to me so I have to write as above. Folks have kicked this error around a lot. Read the priors.

I am not sure but I have added more of my code. I have look though it for past couple months and still no luck.

SearchAllRecords.aspx.vb

<%@ Page Language="VB" AutoEventWireup="false" MasterPageFile="~/MasterPage.master" CodeFile="SearchAllRecords.aspx.vb" Inherits="UI_SearchAllRecords" %>

<asp:Content id="Home_Content2" ContentPlaceHolderID="ContentPH_main" runat="server">
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" DataKeyNames="ID" 
    AllowSorting="True"  OnSorting="GridView1_Sorting" AllowPaging="true" PageSize="9" OnPageIndexChanging="GridView1_PageIndexChanging">
        <Columns>
            <asp:TemplateField  runat="server">
                <ItemTemplate>
                    <asp:HyperLink ID="lnkView" runat="server" Visible="true" NavigateUrl='<%# Eval("ID", "View.aspx?ID={0}") %>' OnClick="window.open(this.href,'targetWindow','width=1000,height=1000,scrollbars=1,resizable=1'); return false;">View</asp:HyperLink>
                            </ItemTemplate>
                    </asp:TemplateField>
                <asp:TemplateField>
                <ItemTemplate>
                    <asp:HyperLink ID="lnkEdit" runat="server" Visible="true" NavigateUrl='<%# Eval("ID", "Edit.aspx?ID={0}") %>' OnClick="window.open(this.href,'targetWindow','width=1000,height=1000,scrollbars=1,resizable=1'); return false;">Edit</asp:HyperLink>
                </ItemTemplate>
            </asp:TemplateField>

            <asp:BoundField DataField="ID" HeaderText="ID" ReadOnly="True" SortExpression="ID" Visible="False" />
            'more bound fields
            ... 
    </asp:GridView>
</asp:Content>

'golbal variable
Dim sortField As String

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
       If Not IsPostBack Then
        Dim da As SqlDataAdapter
        Dim ds As DataSet = New DataSet()
        Dim dt As DataTable = New DataTable
        Dim sqlConn As New SqlConnection(myConnectionString)
        Dim query1 As String = "SELECT * FROM [mytable] ORDER BY Created_dt DESC;"

        Try
            sqlConn.Open()

            Dim cmd = New SqlCommand(query1, sqlConn)
            da = New SqlDataAdapter(cmd)
            Dim builder As SqlCommandBuilder = New SqlCommandBuilder(da)
            da.Fill(ds, "mytable")
            Dim a As Integer = ds.Tables("mytable").Rows.Count
            If a = 0 Then
                ErrorMessage.Text = "0 results found."
            End If

            da.Fill(dt)
            ViewState("SaveData") = dt
            GridView1.DataSource = ViewState("SaveData")
            GridView1.DataBind()

            sqlConn.Close()
        Catch ex As Exception
            ErrorMessage.Text = "error"
        End Try
       End If
   End Sub

    Protected Sub GridView1_Sorting(ByVal sender As Object, ByVal e As GridViewSortEventArgs)
        ' '' Retrieve the data source from session state.
        Dim dt As DataTable = CType(ViewState("SaveData"), DataTable)

        sortField = e.SortExpression
        If Trim(ViewState("sortMode")) <> "" Then
            If ViewState("sortMode").ToString().Trim().Equals("ASC") Then
                ViewState("sortMode") = "DESC"
            Else
                ViewState("sortMode") = "ASC"
            End If
        Else
            ViewState("sortMode") = "ASC"
        End If

        Dim dv As New DataView(dt)
        dv.Sort = sortField.Trim() & " " & ViewState("sortMode")
        GridView1.DataSource = dv
        GridView1.DataBind()
    End Sub

    ' For next page - footer
    Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
        GridView1.PageIndex = e.NewPageIndex

        BindGridData()
    End Sub

Edit.aspx.vb

<%@ Page Language="VB" AutoEventWireup="false" MasterPageFile="~/MasterPage.master" CodeFile="Edit.aspx.vb" Inherits="UI_Edit" %>

<asp:Content id="Home_Content2" ContentPlaceHolderID="ContentPH_main" runat="server">
    <asp:TextBox ID="IDNumberTB" class="form-control input-sm" runat="server"></asp:TextBox>
    'more textbox
    ...
    <asp:Button ID="UpdateB" class="btn btn-primary center-block" runat="server" Text="Update Record" />
</asp:Content>