Question

I have a button and an image in update panel. How do I force the image refresh by clicking on the button?

update

    <b>Enter the code</b>
     <asp:UpdatePanel runat="server">
        <ContentTemplate>
          <uc:TextBox ID="txtCaptcha" runat="server" />
          <asp:Button ID="btnRefreshCaptcha" runat="server" Text="Refresh the code" CausesValidation="false" onclick="btnRefreshCaptcha_Click" />
          </ContentTemplate>
          <Triggers>
            <asp:AsyncPostBackTrigger ControlID="btnRefreshCaptcha" EventName="Click" />
          </Triggers>
    </asp:UpdatePanel>

Answer 1

Add random value parameter to the end of your image url and change that on each update

kind of ImageUrl = baseUrl + “?” + new Random().Next()