India Specific features have been moved to a separate app.
Therefore HSN/SAC Doctype is removed from ERPNext in version-14.
Solutions:
- You plan to use India Specific features → Install respective app.
- You do not plan to use India Specific features → Delete custom field gst_hsn_codefrom Item
- You need the field but not the app → edit custom field. set fieldtype to Data and remove GST HSN Code from options