CSV.read Illegal quoting in line x

Try forcing double quote character " as quote char:

require 'csv'
CSV.foreach(file,{headers: :first_row, quote_char: "\x00"}) do |line|
  p line
end

Don't let CSV both read and parse the file.

Just read the file yourself and hand each line to CSV.parse_line, and then rescue any exceptions it throws.

I had this problem in a line like 123,456,a"b"c

The problem is the CSV parser is expecting ", if they appear, to entirely surround the comma-delimited text.

Solution use a quote character besides " that I was sure would not appear in my data:

CSV.read(filename, :quote_char => "|")

The liberal_parsing option is available starting in Ruby 2.4 for cases like this. From the documentation:

When set to a true value, CSV will attempt to parse input not conformant with RFC 4180, such as double quotes in unquoted fields.

To enable it, pass it as an option to the CSV read/parse/new methods:

CSV.read(filename, liberal_parsing: true)

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