Question

I use the following directive in my aspx page:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="myWebParts._Default" %>
<%@ Register Namespace="myWebParts" TagPrefix="myWebParts_tag" %>

And my page has code snippet like this:

        <ZoneTemplate>
          <myWebParts_tag:HelloWorldWebPart runat="server" ID="_wp1" />
        </ZoneTemplate>

But I got the following error:

Parser Error Description: An error occurred during the parsing of a
resource required to service this request. Please review the following
specific parse error details and modify your source file
appropriately.

Parser Error Message: Unknown server tag
‘myWebParts_tag:HelloWorldWebPart’.

What’s wrong? Thanks.

Answer 1

Your register directive is missing either an assembly or a src information.

• If you want to reference a whole namespace of controls in another assembly, add the assembly name with assembly="AssemblyName".
• If you want to add a single user control in the current assembly, add the location via src="LocationOfUserControl.ascx.

See MSDN for more info on the @Register directive.