Question 136 - Certified B2B Commerce Developer discussion

The root cause of why the custom field MyCustomField__c has no values and no column header in the CSV file is that the user does not have access to the field. A user's access to a field is determined by their profile and permission sets, which define their field-level security settings. Field-level security settings control whether a user can see, edit, or delete the value for a particular field on an object. If a user does not have access to a field, they will not be able to view or modify its value in any interface, including Data Loader. Data Loader is a tool that allows users to import or export data between Salesforce and CSV files. When using Data Loader to export data from an org, Data Loader will only include fields that are accessible to the user based on their field-level security settings. If a user does not have access to a field, Data Loader will not include that field in the CSV file, neither as a column header nor as a value. The user needs to install a specific Zulu JDK that is recommended by Salesforce is not the root cause of why MyCustomField__c has no values and no column header in the CSV file, as it is not related to field access or Data Loader functionality. A mapping file was not used when the data was loaded in is not the root cause either, as it is not related to field access or Data Loader functionality. A mapping file is an optional file that maps fields between Salesforce objects and CSV files when using Data Loader to import or export data. The user has rights to the field but there are no values in it is not the root cause either, as it contradicts the fact that MyCustomField__c has no column header in the CSV file. If the user had rights to the field but there were no values in it, Data Loader would still include MyCustomField__c as a column header in the CSV file, but leave its values blank. Salesforce

Reference: [Data Loader Guide: Export Data from Salesforce], [Data Loader Guide: Field Mapping], [Salesforce Help: Set Field-Level Security]