UnicodeDecodeError in Python 3 when importing a CSV file

From the python docs, you have to set the encoding for the file. Here is an example from the site:

import csv

 with open('some.csv', newline='', encoding='utf-8') as f:
   reader = csv.reader(f)
   for row in reader:
     print(row)

Edit: Your problem appears to happen with printing. Try using pretty printer:

import csv
import pprint

with open('some.csv', newline='', encoding='utf-8') as f:
  reader = csv.reader(f)
  for row in reader:
    pprint.pprint(row)

Another option is to cover up the errors by passing an error handler:

with open('some.csv', newline='', errors='replace') as f:
   reader = csv.reader(f)
   for row in reader:
    print(row)

which will replace any undecodable bytes in the file with a "missing character".

It seems your problem boils down to:

print("α")

You could fix it by specifying PYTHONIOENCODING:

$ PYTHONIOENCODING=utf-8 python3 test.py > output.txt

Note:

$ python3 test.py 

should work as is if your terminal configuration supports it, where test.py:

import csv

with open('myfile.csv', newline='', encoding='utf-8') as file:
    for row in csv.reader(file):
        print(row)

If open() has no encoding parameter above then you'll get UnicodeDecodeError with LC_ALL=C.

Also with LC_ALL=C you'll get UnicodeEncodeError even if there is no redirection i.e., PYTHONIOENCODING is necessary in this case (before PEP 538: Legacy C Locale Coercion implemented in Python 3.7+).