"extra data after last expected column" while trying to import a csv file into postgresql

Now you have 7 fields.

You need to map those 6 fields from the CSV into 6 fields into the table.

You cannot map only 3 fields from csv when you have it 6 like you do in:

\COPY agency (agency_name, agency_url, agency_timezone) FROM 'myFile.txt' CSV HEADER DELIMITER ',';

All fields from the csv file need to to be mapped in the copy from command.

And since you defined csv , delimiter is default, you don't need to put it.

Not sure this counts as an answer, but I just hit this with a bunch of CSV files, and found that simply opening them in Excel and re-saving them with no changes made the error go away. IOTW there is possibly some incorrect formatting in the source file that Excel is able to clean up automatically.