convert String to MD5

Rather than trying to hash the string, you should hash an encoded byte sequence. Instead of

>>> import hashlib
>>> hashlib.md5("fred")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Unicode-objects must be encoded before hashing

you should encode it, e.g.:

>>> "fred".encode("utf")
b'fred'
>>> hashlib.md5("fred".encode("utf")).hexdigest()
'570a90bfbf8c7eab5dc5d4e26832d5b1'

In Python 2 you could get away without doing this, and it led to no end of unnoticed bugs. Fortunately Python 3 has much saner unicode support, and distinguishes between bytes and strings.

As the error suggests, your string must be unicode and you have to encode it. Looking at the call you make (from your stack trace):

computeMD5hash("The quick brown fox jumps over the lazy dog")

it looks like you must be running Python 3 where strings are unicode objects. To encode to a byte representation which can then be processed by the hashlib, change this

m.update((string))

to this (if utf-8 is an appropriate encoding for you to use - it depends how you will be using this):

m.update(string.encode('utf-8'))

If this is all news to you, you should probably read the excellent Python 3 Unicode HOWTO.

---

Also, while I'm here, your code has some other issues

• some unecessary bits - no need for the from hashlib import line or the temporary md5string.
• it's bad form to import modules from within a function, so import hashlib should be moved to module scope.
• the function is returning the digest() which is raw binary, and from your stack trace it looks like you're expecting the hexdigest() instead which is the same thing represented as a hexadecimal string.

To fix and tidy it all up, try this:

import hashlib

def computeMD5hash(my_string):
    m = hashlib.md5()
    m.update(my_string.encode('utf-8'))
    return m.hexdigest()