How to manage null value while copy data from csv

when I am uploading data (CSV File) using the COPY command. I am getting below mention error.

ERROR:  null value in column "adj_type" violates not-null constraint.

When I define null it gives no error message, but how to manage null value n data without defining it, because there is many more columns. when it defines null it gives an error if null value comes you are violating null.

Please suggest how to manage null value in postgresql?

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