What does Error code 15428014 indicate in eMAM Premiere panel?

What does "Error code 15428014" indicate in eMAM Premiere panel?

Error code 15428014: This message appears during export when the required metadata fields are empty.
  • Fill in all the required custom metadata fields.  Some fields are required so users can organize and find content in the eMAM system.  For clarification, ask your Unit Admin or the Super Admin.