diff --git a/frappe/core/doctype/language/language.py b/frappe/core/doctype/language/language.py
index 83d68acb36..8c7e01cb62 100644
--- a/frappe/core/doctype/language/language.py
+++ b/frappe/core/doctype/language/language.py
@@ -14,7 +14,7 @@ def export_languages_json():
 	languages = frappe.db.get_all('Language', fields=['name', 'language_name'])
 	languages = [{'name': d.language_name, 'code': d.name} for d in languages]
 
-	languages.sort(lambda a,b: 1 if a['code'] > b['code'] else -1)
+	languages.sort(key = lambda a: a['code'])
 
 	with open(frappe.get_app_path('frappe', 'geo', 'languages.json'), 'w') as f:
 		f.write(frappe.as_json(languages))
diff --git a/frappe/core/page/data_import_tool/data_import_tool.py b/frappe/core/page/data_import_tool/data_import_tool.py
index 0bf1e97bb2..8338848561 100644
--- a/frappe/core/page/data_import_tool/data_import_tool.py
+++ b/frappe/core/page/data_import_tool/data_import_tool.py
@@ -36,7 +36,7 @@ def import_file_by_path(path, ignore_links=False, overwrite=False, submit=False,
 
 def export_csv(doctype, path):
 	from frappe.core.page.data_import_tool.exporter import get_template
-	with open(path, "w") as csvfile:
+	with open(path, "wb") as csvfile:
 		get_template(doctype=doctype, all_doctypes="Yes", with_data="Yes")
 		csvfile.write(frappe.response.result.encode("utf-8"))
 
diff --git a/frappe/core/page/data_import_tool/exporter.py b/frappe/core/page/data_import_tool/exporter.py
index 4f7bf8a067..7920059957 100644
--- a/frappe/core/page/data_import_tool/exporter.py
+++ b/frappe/core/page/data_import_tool/exporter.py
@@ -81,7 +81,7 @@ def get_template(doctype=None, parent_doctype=None, all_doctypes="No", with_data
 			if field and ((select_columns and f[0] in select_columns[dt]) or not select_columns):
 				tablecolumns.append(field)
 
-		tablecolumns.sort(lambda a, b: int(a.idx - b.idx))
+		tablecolumns.sort(key = lambda a: int(a.idx))
 
 		_column_start_end = frappe._dict(start=0)
 
diff --git a/frappe/custom/doctype/custom_field/custom_field.py b/frappe/custom/doctype/custom_field/custom_field.py
index c81ad6cdf4..6eb3eef544 100644
--- a/frappe/custom/doctype/custom_field/custom_field.py
+++ b/frappe/custom/doctype/custom_field/custom_field.py
@@ -18,8 +18,8 @@ class CustomField(Document):
 			if not self.label:
 				frappe.throw(_("Label is mandatory"))
 			# remove special characters from fieldname
-			self.fieldname = filter(lambda x: x.isdigit() or x.isalpha() or '_',
-				cstr(self.label).lower().replace(' ','_'))
+			self.fieldname = "".join(filter(lambda x: x.isdigit() or x.isalpha() or '_',
+				cstr(self.label).lower().replace(' ','_')))
 
 		# fieldnames should be lowercase
 		self.fieldname = self.fieldname.lower()
diff --git a/frappe/desk/doctype/desktop_icon/desktop_icon.py b/frappe/desk/doctype/desktop_icon/desktop_icon.py
index 1319ffba49..0787af88f7 100644
--- a/frappe/desk/doctype/desktop_icon/desktop_icon.py
+++ b/frappe/desk/doctype/desktop_icon/desktop_icon.py
@@ -95,7 +95,7 @@ def get_desktop_icons(user=None):
 				icon.hidden = 1
 
 		# sort by idx
-		user_icons.sort(lambda a, b: 1 if a.idx > b.idx else -1)
+		user_icons.sort(key = lambda a: a.idx)
 
 		# translate
 		for d in user_icons:
diff --git a/frappe/desk/form/linked_with.py b/frappe/desk/form/linked_with.py
index e5192b1edb..39850c4a16 100644
--- a/frappe/desk/form/linked_with.py
+++ b/frappe/desk/form/linked_with.py
@@ -119,7 +119,7 @@ def _get_linked_doctypes(doctype):
 		if not dt in ret:
 			ret[dt] = {"get_parent": True}
 
-	for dt in ret.keys():
+	for dt in list(ret.keys()):
 		try:
 			doctype_module = load_doctype_module(dt)
 		except ImportError:
diff --git a/frappe/email/queue.py b/frappe/email/queue.py
index 0452cba5bc..b0d903e770 100755
--- a/frappe/email/queue.py
+++ b/frappe/email/queue.py
@@ -478,7 +478,7 @@ def prepare_message(email, recipient, recipients_list):
 	if email.add_unsubscribe_link and email.reference_doctype: # is missing the check for unsubscribe message but will not add as there will be no unsubscribe url
 		unsubscribe_url = get_unsubcribed_url(email.reference_doctype, email.reference_name, recipient,
 		email.unsubscribe_method, email.unsubscribe_params)
-		message = message.replace("<!--unsubscribe url-->", quopri.encodestring(unsubscribe_url))
+		message = message.replace("<!--unsubscribe url-->", quopri.encodestring(unsubscribe_url.encode()).decode())
 
 	if email.expose_recipients == "header":
 		pass
@@ -494,7 +494,7 @@ def prepare_message(email, recipient, recipients_list):
 				email_sent_message = _("This email was sent to {0} and copied to {1}").format(email_sent_to,email_sent_cc)
 			else:
 				email_sent_message = _("This email was sent to {0}").format(email_sent_to)
-			message = message.replace("<!--cc message-->", quopri.encodestring(email_sent_message))
+			message = message.replace("<!--cc message-->", quopri.encodestring(email_sent_message.encode()).decode())
 
 		message = message.replace("<!--recipient-->", recipient)
 
diff --git a/frappe/model/document.py b/frappe/model/document.py
index 5b64796c5b..38dc71f73a 100644
--- a/frappe/model/document.py
+++ b/frappe/model/document.py
@@ -1004,7 +1004,7 @@ class Document(BaseDocument):
 
 	def get_signature(self):
 		"""Returns signature (hash) for private URL."""
-		return hashlib.sha224(get_datetime_str(self.creation)).hexdigest()
+		return hashlib.sha224(get_datetime_str(self.creation).encode()).hexdigest()
 
 	def get_liked_by(self):
 		liked_by = getattr(self, "_liked_by", None)
diff --git a/frappe/translate.py b/frappe/translate.py
index 6ddd7bf3b1..7f47954300 100644
--- a/frappe/translate.py
+++ b/frappe/translate.py
@@ -555,7 +555,7 @@ def write_csv_file(path, app_messages, lang_dict):
 	:param app_messages: Translatable strings for this app.
 	:param lang_dict: Full translated dict.
 	"""
-	app_messages.sort(lambda x,y: cmp(x[1], y[1]))
+	app_messages.sort(key = lambda x: x[1])
 	from csv import writer
 	with open(path, 'wb') as msgfile:
 		w = writer(msgfile, lineterminator='\n')
@@ -684,7 +684,7 @@ def deduplicate_messages(messages):
 	op = operator.itemgetter(1)
 	messages = sorted(messages, key=op)
 	for k, g in itertools.groupby(messages, op):
-		ret.append(g.next())
+		ret.append(next(g))
 	return ret
 
 def get_bench_dir():
diff --git a/frappe/utils/data.py b/frappe/utils/data.py
index e2752f6dfe..6ca611be88 100644
--- a/frappe/utils/data.py
+++ b/frappe/utils/data.py
@@ -734,7 +734,7 @@ def get_filter(doctype, f):
 	from frappe.model import default_fields, optional_fields
 
 	if isinstance(f, dict):
-		key, value = f.items()[0]
+		key, value = next(iter(f.items()))
 		f = make_filter_tuple(doctype, key, value)
 
 	if not isinstance(f, (list, tuple)):
diff --git a/frappe/utils/file_manager.py b/frappe/utils/file_manager.py
index de0ebdf12f..822b63e240 100644
--- a/frappe/utils/file_manager.py
+++ b/frappe/utils/file_manager.py
@@ -301,6 +301,8 @@ def get_file_path(file_name):
 	return file_path
 
 def get_content_hash(content):
+	if isinstance(content, text_type):
+		content = content.encode()
 	return hashlib.md5(content).hexdigest()
 
 def get_file_name(fname, optional_suffix):
diff --git a/frappe/utils/password_strength.py b/frappe/utils/password_strength.py
index f94893ed53..5591cfbb14 100644
--- a/frappe/utils/password_strength.py
+++ b/frappe/utils/password_strength.py
@@ -3,14 +3,14 @@
 
 from __future__ import unicode_literals
 
-import zxcvbn
+from zxcvbn import zxcvbn
 import frappe
 from frappe import _
 
 def test_password_strength(password, user_inputs=None):
 	'''Wrapper around zxcvbn.password_strength'''
-	result = zxcvbn.password_strength(password, user_inputs)
-	result['feedback'] = get_feedback(result['score'], result['match_sequence'])
+	result = zxcvbn(password, user_inputs)
+	result['feedback'] = get_feedback(result['score'], result['sequence'])
 	return result
 
 # NOTE: code modified for frappe translations
@@ -37,7 +37,7 @@ def get_feedback (score, sequence):
 	"""
 	Returns the feedback dictionary consisting of ("warning","suggestions") for the given sequences.
 	"""
-	minimum_password_score = frappe.db.get_single_value("System Settings", "minimum_password_score")
+	minimum_password_score = int(frappe.db.get_single_value("System Settings", "minimum_password_score"))
 
 	global default_feedback
 	# Starting feedback
diff --git a/frappe/utils/verified_command.py b/frappe/utils/verified_command.py
index 08fe7c2ab6..31e2c80804 100644
--- a/frappe/utils/verified_command.py
+++ b/frappe/utils/verified_command.py
@@ -17,8 +17,8 @@ def get_signed_params(params):
 	if not isinstance(params, string_types):
 		params = urlencode(params)
 
-	signature = hmac.new(params)
-	signature.update(get_secret())
+	signature = hmac.new(params.encode())
+	signature.update(get_secret().encode())
 	return params + "&_signature=" + signature.hexdigest()
 
 def get_secret():
@@ -36,7 +36,7 @@ def verify_request():
 
 		given_signature = hmac.new(params.encode("utf-8"))
 
-		given_signature.update(get_secret())
+		given_signature.update(get_secret().encode())
 		valid = signature == given_signature.hexdigest()
 
 	if not valid:
diff --git a/frappe/website/doctype/blog_post/test_blog_post.py b/frappe/website/doctype/blog_post/test_blog_post.py
index a6c1668045..d38349ba07 100644
--- a/frappe/website/doctype/blog_post/test_blog_post.py
+++ b/frappe/website/doctype/blog_post/test_blog_post.py
@@ -17,7 +17,7 @@ class TestBlogPost(unittest.TestCase):
 
 		self.assertTrue(response.status_code, 200)
 
-		html = response.get_data()
+		html = response.get_data().decode()
 		self.assertTrue('<article class="blog-content" itemscope itemtype="http://schema.org/BlogPosting">' in html)
 
 	def test_generator_not_found(self):
diff --git a/frappe/website/utils.py b/frappe/website/utils.py
index 7a80d03f85..9388116c6a 100644
--- a/frappe/website/utils.py
+++ b/frappe/website/utils.py
@@ -19,7 +19,7 @@ def delete_page_cache(path):
 def find_first_image(html):
 	m = re.finditer("""<img[^>]*src\s?=\s?['"]([^'"]*)['"]""", html)
 	try:
-		return m.next().groups()[0]
+		return next(m).groups()[0]
 	except StopIteration:
 		return None
 
diff --git a/frappe/www/list.py b/frappe/www/list.py
index 77975e73d6..073a3171c4 100644
--- a/frappe/www/list.py
+++ b/frappe/www/list.py
@@ -113,7 +113,7 @@ def prepare_filters(doctype, controller, kwargs):
 				filters[key] = val
 
 	# filter the filters to include valid fields only
-	for fieldname, val in filters.items():
+	for fieldname, val in list(filters.items()):
 		if not meta.has_field(fieldname):
 			del filters[fieldname]
 
diff --git a/requirements.txt b/requirements.txt
index 44a441e34d..b5c564eede 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -37,7 +37,7 @@ cryptography
 pyopenssl
 ndg-httpsclient
 pyasn1
-zxcvbn
+zxcvbn-python
 psutil
 unittest-xml-reporting
 oauthlib