I can't reproduce the exact error you described, but i can tell you that on my system, i had to set...

$dbh->{'csv_eol'} = "\n";
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...because DBD::CSV seems to assume windows line terminators in your files, regardless of what $/ is.

I can imagine that in some version of DBD::CSV, that may come across as an error because it never finds the end of the first line.