The field definitions file is located in ‘EasyCatalog Workspace > DataSourceName > Data > Fields.xml’. This would be displayed if EasyCatalog was unable to read this file, this file should not be edited manually as mistakes can occur resulting in this error message. The file could have also become corrupted, in which case a backup of the data source folder would need to be restored.
Regular backups should be made of the data source folder to correct issues like this; the location of the workspace folder is shown in EasyCatalog’s general preferences. From the InDesign application menu (on Macintosh) or the Edit menu (on Windows), select Preferences->EasyCatalog. Press the Reveal button, this will open up the folder on the filesystem where the appropriate data source folder can be copied and backed up.
