Vocabulary_reference Error, not null constraint raises

1

I am loading concept data into an postgreSQL database using csv files downloaded from Athena. Most of the data has loaded successfully except for the vocabulary.

Here is what I used
\COPY VOCABULARY FROM ‘VOCABULARY.csv’ WITH DELIMITER E’\t’ CSV HEADER QUOTE E’\b’ ;

Here is the error
ERROR: null value in column “vocabulary_reference” violates not-null constraint
DETAIL: Failing row contains (Plan, Health Plan - contract to administer healthcare transactions by …, null, null, 32471).
CONTEXT: COPY vocabulary, line 14: “Plan Health Plan - contract to administer healthcare transactions by the payer, facilitated by the s…”

I will appreciate any guidance on how to fix this?

Thank you