ASP.NET Circular File Reference

“Circular file references are not allowed” error occurs while building or deploying asp.net website, this can happen due to differnt reasons:

1. When one ASCX control references another which contains a reference back to the first one
2. When an ASCX control references another in a different directory that also contains other controls that reference back to the first one
3. When a ASPX page references ASCX control in a different folder, that also contain other pages that reference this control

There might be other reasons as well, ASP.NET website compiles into different libraries, which reference each other as well, .NET compiler bt default build libraries in batch, means files in one folder are batched together in a single library depending on the dependencies.

In "batch mode," the output of multiple source files is compiled into single assemblies according to the type of file, file dependencies, and other criteria. The result is a target site containing a set of assemblies with the executable code for the original source files.

<system.web>
    <compilation debug="true" batch="false">
    </compilation>
</system.web>

Here batch="false"tells the ASP.NET compiler to not batch assemblies, and create an assembly for each web form and user control. When it is set to true, then the compiler will batch assemblies.

Circular reference is a by-product of the ASP.NET compiler "batching" assemblies together for performance reasons. By default it will take the web forms and user controls in a folder and compile them into an assembly.

There are several ways to solve this issue, but we recommend moving the referenced pages (e.g. Pages2.aspx.vb and Pages3.aspx.vb) to their own folder. By default, the ASP.NET compiler will create a separate assembly containing these pages and the circular reference will be removed between Assembly A and B.