Question

I get this message at runtime of ASP.NET 2 page :

The page ‘MyFolder/blabla.aspx’ cannot use the user control ‘MyFolder/MyControl.ascx’, because it is registered in web.config and lives in the same directory as the page.

Of course I can separate them to 2 different folders and thus solve the problem, but the question is :

WTF !?!?! Why I can’t put them in the same folder ?!
Why can’t they all .. get along !?! 🙂

Thanks

Answer 1

This limitation is by design due to an internal design consideration re: performance.

See here for further info.

Remarks

The TagPrefixInfo class allows you to programmatically access and
modify tag-prefix information stored in a configuration file. It
provides the same functionality as the ASP.NET @Register
directive. Tag prefixes associate a “namespace” in ASP.NET to the
assemblies and namespaces that must be included for custom controls
and user controls to work properly. TagPrefixInfo objects are stored
as members of a TagPrefixCollection object. The
TagPrefixCollection class allows you to programmatically access
and modify the controls subsection of the pages section of a
configuration file.

TagPrefixInfo objects are added to the collection using the add
element and specifying a value for the tagPrefix attribute along
with values for other relevant attributes. The other required
information varies based on the kind of control you will use with the
specified tag prefix:

• If it is a user control, you must define the TagPrefix, TagName, and Source properties.
• If it is a custom control, you must define the TagPrefix, Namespace, and Assembly properties. The Assembly
  property is not required if the control is in the application code
  directory. The same tagPrefix value can be used to map to multiple
  assemblies or namespaces.

Note When a source is specified, the user control itself must not be in the same directory as the page. If it is, you get a run-time
error when you attempt to load the page.