Timer control triiggers updatepanel in 5 seconds and I get a sys.webforms,PageRequestManagerServerErrorException
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    <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="ChatUserControl.ascx.cs"
        Inherits="MetamorphismApp.ChatUserControl" %>
    
    <asp:Timer ID="timer1" runat="server" OnTick="timer1_Tick" Interval="5000">
    </asp:Timer>
    <div id="divChatWindow" class="clChatWindow">
        <div>
            <asp:Label runat="server" Text='<%# Eval("username") %>' class="divHeader" ID="lblChatFriend"></asp:Label>
            <asp:Image ID="imgFriend" runat="server" CssClass="classFriendImage" />
            <asp:LinkButton ID="lbClose" runat="server" CommandName="Close" CssClass="lbClose"
                OnClick="lbClose_Click">Close</asp:LinkButton></div>
        <div class="chatText" id="idChatText" runat="server">
            <asp:UpdatePanel ID="UpdatePanel" runat="server">
                <Triggers>
                    <asp:AsyncPostBackTrigger ControlID="timer1" EventName="Tick" />
                    <asp:AsyncPostBackTrigger ControlID="btnSendChat" EventName="Click" />
                </Triggers>
                <ContentTemplate>
                    <asp:Repeater runat="server" ID="rpChatMessages">
                        <ItemTemplate>
                            <asp:Image ID="imageForFriend" runat="server" CssClass="clFriendsImage" ImageUrl='<%# "HttpImageHandler.jpg?username=" +  DataBinder.Eval(Container.DataItem,"fromusername").ToString() %>' />
                            <asp:Label ID="chatMessage" runat="server" Text='<%# Eval("Message") %>'></asp:Label>
                            <br>
                        </ItemTemplate>
                    </asp:Repeater>
                </ContentTemplate>
            </asp:UpdatePanel>
        </div>
        <asp:TextBox ID="txtChatMessage" runat="server" Width="142px" CssClass="clChatMessage" EnableViewState="true"
            TextMode="MultiLine"></asp:TextBox>
        <asp:LinkButton ID="btnSendChat" runat="server" CommandName="Insert" CommandArgument='<%# Eval("username") %>'
            OnClick="btnSendChat_Click" CssClass="btnSendChat">Send</asp:LinkButton>
       
    </div>

I want to use updatepanel triggered by a timer control and after 5 seconds I get a sys.webforms error. I dont wanna populate my repeater using a webservice to be called via jquery and binding the data to the repeater. I want to use the updatepanel for data population. I have read several articles to avoid this error but havent found a solution yet. If I change asyncpostback trigger to postbacktrigger the page does a postback which I dont want to happen. I want to use updatepanel to solve this issue. What should I do?