Ran into this issue today. Just wanted to share my resolution method for reference purposes.
For me it was LSMW related, and the error "EDI: Field SEGNAM in data record is default" was displayed because the input file used (a .txt file) contained a line break (Alt+Enter) in one of the records. The original source was an Excel file. So, remove line breaks, and the error is gone. It was as simple as that...