BE0026: Unable to determine default topic in '[tocFile]'.

Error BE0026: Unable to determine default topic in '[tocFile]'. You may need to mark one as the default topic manually.

This error occurs when the build process is updating the table of contents with entries for additional and conceptual content and it is unable to determine the default topic be extracting it from the indicated table of contents file. This usually occurs when building a help file that does not contain any API reference content.

Add a site map file (HTML additional content) or a content layout file (conceptual content) to the project and use it to arrange the additional content/conceptual content items. In addition, mark one of the entries as the default topic within the editor for the layout file.

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