Error in parsing asp.net page

Question

Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled Details: Error parsing near <HTML><HEAD><TITLE><

Please help me out , this is bugging me....

<body>
    <form id="form1" runat="server">
    <aspAtlas:ScriptManager ID="MyScriptManager" runat="server" AllowCustomErrorsRedirect="true">
    </aspAtlas:ScriptManager>
    <div class="headerborder" id="hd_SubmissionGuidelines">
        <aspAtlas:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <table width="100%" border="0" cellspacing="0" cellpadding="0" align="center">
                    <tr>
                        <td class="t_head">

                            <asp:HiddenField ID="hfdSizeAttached" runat="server" />
                            <asp:HiddenField ID="hfdConfidentialDoc" runat="server" />
                            <asp:HiddenField ID="hfdJustificationDoc" runat="server" />
                            <asp:HiddenField ID="hfdRedactedVersionDoc" runat="server" />
                            <asp:Button ID="btnHiddenAttachDoc" runat="server" Style="visibility: hidden" OnClick="btnHiddenAttachDoc_Click" />
                            <asp:HiddenField ID="hdnDocsAttached" runat="server"></asp:HiddenField>
                        </td>
                    </tr>
                </table>
            </ContentTemplate>
            <Triggers>
                <aspAtlas:AsyncPostBackTrigger ControlID="btnAgree" EventName="Click" />
                <aspAtlas:PostBackTrigger ControlID="btnSubmit" />
                <aspAtlas:AsyncPostBackTrigger ControlID="btnBack" EventName="Click" />
                <aspAtlas:AsyncPostBackTrigger ControlID="btnHiddenAttachDoc" EventName="Click" />
            </Triggers>
        </aspAtlas:UpdatePanel>
    </div>
    <aspAtlas:UpdatePanel ID="UpdPagePanel" runat="server">
        <ContentTemplate>
            <asp:Panel ID="pnlSubmissionGuidelines" runat="server">
                <div class="div_main" id="hd_MainGuidelines">
                    <div>
                        <table width="100%" border="0" cellspacing="0" cellpadding="0" align="center">
                            <tr>
                                <td class="t_guidelines_head">
                                    Doc Submit
                                </td>
                            </tr>
                            <tr>
                                <td class="t_guidelines_subhead">
                                    Definitions:
                                </td>
                            </tr>
                            <tr>
                                <td class="t_guidelines_text">
                                    Dummy lines
                                    <br />
                                    <br />
                                   Dummy lines
                                    <br />
                                    <br />
                                    dummy lines
                                    <br />
                                    <br />
                                   dummy lines
                                </td>
                            </tr>
                            <tr>
                                <td class="t_guidelines_subhead">
                                    dummy lines

                                </td>
                            </tr>
                            <tr>
                                <td class="t_guidelines_text">
                                    <font style="text-decoration: underline">Process</font>
                                    <br />
                                    <br />
                                    dummy lines
                                    <br />
                                    <br />
                                   dummy lines
                                    <br />
                                   dummy lines
                                    <br />
                                    <br />
                                    <font class="t_guidelines_ul">Trade Secret </font>
                                    <br />
                                    <font class="t_guidelines_ul">Sample </font><br />
                                    <font class="t_guidelines_ul">Sample text</font>
                                    <br />
                                    <br />
                                    dummy lines
                                                                       <br />
                                    <br />
                                    <font style="text-decoration: underline">Sample text</font>
                                    <br />
                                    <br />
                                     dummy lines
                                    <br />
                                    <br />
                                    <font class="t_guidelines_ul">Sample  ddffvdffvdfgvfv
                                        simple text; </font>
                                    <br />
                                    <font class="t_guidelines_ul">simple text; </font>
                                    <br />
                                    <font class="t_guidelines_ul">simple text; </font>
                                    <br />
                                    <font class="t_guidelines_ul">simple text;</font><br />
                                    <font class="t_guidelines_ul">simple text; </font>
                                    <br />
                                    <font class="t_guidelines_ul">and</font><br />
                                    <font class="t_guidelines_ul">simple text.</font><br />
                                    <br />
                                    <br />
                                    <font style="text-decoration: underline">simple text</font>
                                    <br />
                                    <br />
                                    simple text
                                    <br />
                                    <br />
                                </td>
                            </tr>
                            <tr>
                                <td align="center">
                                    <asp:Button ID="btnAgree" runat="server" CssClass="top_button" OnClick="btnAgree_Click"
                                        Text="I Agree" />
                                    <asp:Button ID="btnDisagree" runat="server" CssClass="top_button" Text="I Disagree"
                                        OnClientClick="javascript:window.close();" />
                                </td>
                            </tr>
                        </table>
                    </div>
                </div>
            </asp:Panel>
            <asp:Panel ID="pnlConfidentialDocuments" runat="server">
                <table width="99%" cellspacing="0" style="border-left: 1px solid #C3C3C3; border-right: 1px solid #C3C3C3;
                    border-bottom: 1px solid #C3C3C3;" cellpadding="0" align="center" id="Table1">
                    <tr class="headerborder">
                        <td class="t_head">
                            <span id="Conf_Docs_Close" style="cursor: hand" onclick="hideArea('Conf_Docs','Conf_Docs_Close','Conf_Docs_Open')">
                                -</span><span id="Conf_Docs_Open" onclick="showArea('Conf_Docs','Conf_Docs_Open','Conf_Docs_Close')"
                                    style="cursor: hand; display: none">+</span> Add Confidential Documents
                        </td>
                    </tr>
                    <tr id="Conf_Docs">
                        <td>
                            <table width="100%" border="0" cellspacing="0" cellpadding="0" align="left" id="Table2">
                                <tr valign="top">
                                    <td class="astrik">
                                    </td>
                                    <td class="form_field">
                                        <img style="vertical-align: top" alt="Required Field" src="../Images/MandatoryField.gif" />
                                        <asp:Label ID="LblDocType" runat="server"><label for='<%= ddlDocumentType.ClientID %>'>Document Type</label></asp:Label>
                                    </td>
                                    <td class="form_element">
                                        <asp:DropDownList ID="ddlDocumentType" runat="server" CssClass="form_select">
                                        </asp:DropDownList>
                                        <a id="lnkDocumentClassificationHelp" runat="server" onclick="window.open('http://google.com');return false;">
                                            <img src="<% =Request.ApplicationPath %>/images/help_icon.gif" alt='Document Classification Help'
                                                width='16' height='16' /></a>
                                    </td>
                                    <td>
                                    </td>
                                </tr>
                                <tr>
                                    <td class="astrik">
                                    </td>
                                    <td class="form_field" style="vertical-align: top">
                                        <img style="vertical-align: top" alt="Required Field" src="../Images/MandatoryField.gif" />
                                        <asp:Label ID="LblDocTitle" runat="server"><label for='<%= txtDocTitle.ClientID %>'>Document Title</label></asp:Label>
                                    </td>
                                    <td class="form_element" colspan="2">
                                        <asp:TextBox ID="txtDocTitle" runat="server" CssClass="textarea_Conf" TextMode="MultiLine"
                                            MaxLength="2000" Rows="10" />
                                        <br />
                                        <asp:Label ID="lblDocTitleLength" runat="server" CssClass="form_label_textareaLength"
                                            Text="Characters remaining: 2000"></asp:Label>
                                    </td>
                                </tr>
                                <tr>
                                    <td colspan="4">
                                        <table width="92%" border="0" cellspacing="0" cellpadding="0" align="left" id="Table3">
                                            <tr>
                                                <td class="form_element" align="right">
                                                    <asp:Button ID="btnAttachDocs" runat="server" CssClass="top_button" Text="Attach Document"
                                                        OnClientClick="javascript:return OpenAttachDocPopup()" />
                                                </td>
                                            </tr>
                                        </table>
                                    </td>
                                </tr>
                            </table>
                        </td>
                    </tr>
                    <tr class="bottomborder">
                        <td class="toptr">
                            <asp:Button ID="btnSubmit" Text="Done" CssClass="top_button" runat="server" OnClientClick="javascript:return Validate();"
                                OnClick="btnSubmit_Click" />
                            <asp:Button ID="btnBack" Text="Back" CssClass="top_button" runat="server" OnClick="btnBack_Click" />
                        </td>
                    </tr>
                </table>
            </asp:Panel>
            <asp:Panel ID="pnlConfidentialDocsGrid" runat="server" Visible="false">
                <table width="100%" border="0" cellspacing="0" cellpadding="0" align="center">
                    <tr>
                        <td class="t_head">
                            Attached Documents
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <asp:DataGrid ID="dgdDocuments" runat="server" Width="100%" OnDeleteCommand="dgdDocuments_Delete"
                                DataKeyField="DocGuidName" AutoGenerateColumns="false" OnItemDataBound="dgdDocuments_ItemDataBound">
                                <HeaderStyle CssClass="t_grid_subheadin" />
                                <ItemStyle CssClass="t_grid_datain" />
                                <AlternatingItemStyle CssClass="t_grid_datainalt" />
                                <Columns>
                                    <asp:TemplateColumn ItemStyle-Width="3%" ItemStyle-HorizontalAlign="Center">
                                        <ItemTemplate>
                                            <asp:Image ID="ImgSecurity" runat="server" ToolTip="Confidential" ImageUrl='<%# DataBinder.Eval(Container.DataItem, "SecurityImageDisplay") %>' />
                                            <asp:Label ID="HiddenSecurity" runat="server" Visible="false" Text='<%# DataBinder.Eval(Container.DataItem, "SecurityImageDisplay") %>' />
                                            <asp:HiddenField ID="hfdIsJustification" runat="server" Value='<%# DataBinder.Eval(Container.DataItem, "IsJustificationDoc").ToString() %>' />
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:TemplateColumn ItemStyle-Width="3" ItemStyle-HorizontalAlign="Center">
                                        <ItemTemplate>
                                            <asp:Image ID="ImgMimeType" runat="server" ImageUrl='<%# DataBinder.Eval(Container.DataItem, "MimeTypeImagePath") %>' />
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:TemplateColumn HeaderText="Document Type" ItemStyle-Width="18%">
                                        <ItemTemplate>
                                            <asp:Label ID="LblType" runat="server" Text='<%# ((WSMatter.IDNameEntity)DataBinder.Eval(Container.DataItem, "DocType")).Name %>'></asp:Label>
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:TemplateColumn HeaderText="Document Title" ItemStyle-Width="50%">
                                        <ItemTemplate>
                                            <asp:Label ID="LblTitle" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "DocTitle")  %>'></asp:Label>
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:TemplateColumn HeaderText="File Name" ItemStyle-Width="16%">
                                        <ItemTemplate>
                                            <asp:Label ID="LblName" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "DocName") %>'></asp:Label>
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:TemplateColumn HeaderText="Size" ItemStyle-Width="10%" ItemStyle-HorizontalAlign="Right">
                                        <ItemTemplate>
                                            <asp:Label ID="LblSize" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "SizetoDisplay") %>'></asp:Label>
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:TemplateColumn ItemStyle-Width="3%" ItemStyle-HorizontalAlign="Center">
                                        <ItemTemplate>
                                            <asp:LinkButton ID="LnkDelete" runat="server" CommandName="Delete"><img src="../Images/nok.gif" alt="Delete"/></asp:LinkButton>
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                </Columns>
                            </asp:DataGrid>
                            <asp:HiddenField ID="HdnTotalSizeAttached" runat="server" />
                        </td>
                    </tr>
                </table>
            </asp:Panel>
        </ContentTemplate>
        <Triggers>
            <aspAtlas:AsyncPostBackTrigger ControlID="btnAgree" EventName="Click" />
            <aspAtlas:PostBackTrigger ControlID="btnSubmit" />
            <aspAtlas:AsyncPostBackTrigger ControlID="btnBack" EventName="Click" />
            <aspAtlas:AsyncPostBackTrigger ControlID="btnHiddenAttachDoc" EventName="Click" />
        </Triggers>
    </aspAtlas:UpdatePanel>
    </form>
</body>

The actual C# code so that we can reproduce the problem or atleast try to understand it.'<HTML><HEAD><TITLE>'< doesn't help at all. — Jeremy Thompson
What do you have on the page, when does this occur ? Do you have Response.Write onto an Update Panel or sorts or maybe check this out — V4Vendetta
Hi Jeremy, I was asking why this error is occurring, As I don't find any such problem in my HTML. , I am trying to paste the code, but it is not working,,, — Rishabh Jain

Unknown Unknown · Accepted Answer · 2012-09-14T07:03:58

As per your code it seems you are not using masterpage, and you have not shown us your tag, so I assume following could help you.

Normally in asp.net webforms, <Head> tag is attributed as runat="server",
So you may try <head runat="server">

Note: I have written it as an answer because there are many comments on the answer, it alerts the moderators. So better new comments get after the answers.

Edit:

This error occurs on the server while processing the response to an asynchronous postback. There are some links to solve this issue, check it they help:

Error in parsing asp.net page

1 Answers