Btrieve v5.x or earlier could not find the extension file for an extended file that the application tried to open.
The Xfh2btr module does not extend files and so this error implies that the file was created outside of the COBOL system. Ensure that the required extended file is available (extension files must be loaded on the logical disk drive specified when the extension was created). In order to access an extended file, both the primary file and its extension file must be online.