diff --git a/applications/admin/controllers/appadmin.py b/applications/admin/controllers/appadmin.py
index 2f780749..3060945c 100644
--- a/applications/admin/controllers/appadmin.py
+++ b/applications/admin/controllers/appadmin.py
@@ -10,6 +10,7 @@ import datetime
 import copy
 import gluon.contenttype
 import gluon.fileutils
+from gluon._compat import iteritems
 
 try:
     import pygraphviz as pgv
@@ -267,7 +268,7 @@ def select():
             else:
                 rows = db(query, ignore_common_filters=True).select(
                     *fields, limitby=(start, stop))
-        except Exception, e:
+        except Exception as e:
             import traceback
             tb = traceback.format_exc()
             (rows, nrows) = ([], 0)
@@ -286,7 +287,7 @@ def select():
             import_csv(db[request.vars.table],
                        request.vars.csvfile.file)
             response.flash = T('data uploaded')
-        except Exception, e:
+        except Exception as e:
             response.flash = DIV(T('unable to parse csv file'), PRE(str(e)))
     # end handle upload csv
 
@@ -454,7 +455,7 @@ def ccache():
         except (KeyError, ZeroDivisionError):
             ram['ratio'] = 0
 
-        for key, value in cache.ram.storage.iteritems():
+        for key, value in iteritems(cache.ram.storage):
             if hp:
                 ram['bytes'] += hp.iso(value[1]).size
                 ram['objects'] += hp.iso(value[1]).count
diff --git a/applications/admin/controllers/default.py b/applications/admin/controllers/default.py
index fea3c3f7..b28c7626 100644
--- a/applications/admin/controllers/default.py
+++ b/applications/admin/controllers/default.py
@@ -15,6 +15,7 @@ from gluon.utils import web2py_uuid
 from gluon.tools import Config
 from gluon.compileapp import find_exposed_functions
 from glob import glob
+from gluon._compat import iteritems, PY2
 import shutil
 import platform
 
@@ -81,7 +82,10 @@ def safe_open(a, b):
             def close(self):
                 pass
         return tmp()
-    return open(a, b)
+    if PY2 or 'b' in b:
+        return open(a, b)
+    else:
+        return open(a, b, encoding="utf8")
 
 
 def safe_read(a, b='r'):
@@ -314,7 +318,7 @@ def site():
     if FILTER_APPS:
         apps = [f for f in apps if f in FILTER_APPS]
 
-    apps = sorted(apps, lambda a, b: cmp(a.upper(), b.upper()))
+    apps = sorted(apps, key=lambda a: a.upper())
     myplatform = platform.python_version()
     return dict(app=None, apps=apps, myversion=myversion, myplatform=myplatform,
                 form_create=form_create, form_update=form_update)
@@ -1152,7 +1156,7 @@ def design():
     # Get all languages
     langpath = os.path.join(apath(app, r=request), 'languages')
     languages = dict([(lang, info) for lang, info
-                      in read_possible_languages(langpath).iteritems()
+                      in iteritems(read_possible_languages(langpath))
                       if info[2] != 0])  # info[2] is langfile_mtime:
     # get only existed files
 
@@ -1288,7 +1292,7 @@ def plugin():
 
     # Get all languages
     languages = sorted([lang + '.py' for lang, info in
-                        T.get_possible_languages_info().iteritems()
+                        iteritems(T.get_possible_languages_info())
                         if info[2] != 0])  # info[2] is langfile_mtime:
     # get only existed files
 
diff --git a/applications/admin/views/default/ticket.html b/applications/admin/views/default/ticket.html
index 2b9a73b1..eb26c849 100644
--- a/applications/admin/views/default/ticket.html
+++ b/applications/admin/views/default/ticket.html
@@ -122,7 +122,7 @@
     {{=XML(snapshot.get('response','no response available in snapshot'))}}
   </div>
 </div>
-{{except Exception, e:}}
+{{except Exception as e:}}
 <!-- this should not happen, just in case... (cannot output normal hmtl as we don't know current open tags) -->
 {{import traceback;tb=traceback.format_exc().replace("\n","\\n") }}
 <script language='javascript'>alert("Exception during snapshot rendering: {{=tb}} ");</script>
diff --git a/applications/admin/views/default/ticket.load b/applications/admin/views/default/ticket.load
index 381eee1d..9a42bba3 100644
--- a/applications/admin/views/default/ticket.load
+++ b/applications/admin/views/default/ticket.load
@@ -117,7 +117,7 @@
         <div class="hide inspect" id="session"><h6>session</h6>{{=BEAUTIFY(snapshot['session'])}}</div>
         <div class="hide inspect" id="response"><h6>response</h6>{{=BEAUTIFY(snapshot['response'])}}</div>
     </div>
-{{except Exception, e:}}
+{{except Exception as e:}}
     <!-- this should not happen, just in case... (cannot output normal hmtl as we don't know current open tags) -->
     {{import traceback;tb=traceback.format_exc().replace("\n","\\n") }}
     <script language='javascript'>alert("Exception during snapshot rendering: {{=tb}} ");</script>
diff --git a/applications/admin/views/layout.html b/applications/admin/views/layout.html
index 748f8f6e..5203dfc6 100644
--- a/applications/admin/views/layout.html
+++ b/applications/admin/views/layout.html
@@ -61,7 +61,7 @@
                 {{if hasattr(T,'get_possible_languages_info'):}}
                 - {{=T('Admin language')}}</span>
                 <select name="adminlanguage" onchange="var date = new Date();cookieDate=date.setTime(date.getTime()+(100*24*60*60*1000));document.cookie='adminLanguage='+this.options[this.selectedIndex].id+'; expires='+cookieDate+'; path=/';window.location.reload()">
-                    {{for langinfo in sorted([(code,info[1]) for code,info in T.get_possible_languages_info().iteritems() if code != 'default']):}}
+                    {{for langinfo in sorted([(code,info[1]) for code,info in iteritems(T.get_possible_languages_info()) if code != 'default']):}}
                     <option {{=T.accepted_language==langinfo[0] and 'selected' or ''}} {{='id='+langinfo[0]}} >{{=langinfo[1]}}</option>
                     {{pass}}
                 </select>
diff --git a/applications/examples/controllers/appadmin.py b/applications/examples/controllers/appadmin.py
index 2f780749..3060945c 100644
--- a/applications/examples/controllers/appadmin.py
+++ b/applications/examples/controllers/appadmin.py
@@ -10,6 +10,7 @@ import datetime
 import copy
 import gluon.contenttype
 import gluon.fileutils
+from gluon._compat import iteritems
 
 try:
     import pygraphviz as pgv
@@ -267,7 +268,7 @@ def select():
             else:
                 rows = db(query, ignore_common_filters=True).select(
                     *fields, limitby=(start, stop))
-        except Exception, e:
+        except Exception as e:
             import traceback
             tb = traceback.format_exc()
             (rows, nrows) = ([], 0)
@@ -286,7 +287,7 @@ def select():
             import_csv(db[request.vars.table],
                        request.vars.csvfile.file)
             response.flash = T('data uploaded')
-        except Exception, e:
+        except Exception as e:
             response.flash = DIV(T('unable to parse csv file'), PRE(str(e)))
     # end handle upload csv
 
@@ -454,7 +455,7 @@ def ccache():
         except (KeyError, ZeroDivisionError):
             ram['ratio'] = 0
 
-        for key, value in cache.ram.storage.iteritems():
+        for key, value in iteritems(cache.ram.storage):
             if hp:
                 ram['bytes'] += hp.iso(value[1]).size
                 ram['objects'] += hp.iso(value[1]).count
diff --git a/applications/examples/controllers/soap_examples.py b/applications/examples/controllers/soap_examples.py
index 7840105e..2d091e80 100644
--- a/applications/examples/controllers/soap_examples.py
+++ b/applications/examples/controllers/soap_examples.py
@@ -44,7 +44,7 @@ def test_soap_sub():
     try:
         ret = client.SubIntegers(a=3, b=2)
         result = ret['SubResult']
-    except SoapFault, sf:
+    except SoapFault as sf:
         result = sf
     response.view = "soap_examples/generic.html"
     return dict(xml_request=client.xml_request, 
diff --git a/applications/examples/models/markmin.py b/applications/examples/models/markmin.py
index 3376bac6..0370df95 100644
--- a/applications/examples/models/markmin.py
+++ b/applications/examples/models/markmin.py
@@ -28,7 +28,7 @@ def get_content(b=None,
 
     try:
         openedfile = openfile()
-    except Exception, IOError:
+    except (Exception, IOError):
         l = 'en'
         openedfile = openfile()
 
diff --git a/applications/welcome/controllers/appadmin.py b/applications/welcome/controllers/appadmin.py
index ddb02548..3060945c 100644
--- a/applications/welcome/controllers/appadmin.py
+++ b/applications/welcome/controllers/appadmin.py
@@ -10,6 +10,7 @@ import datetime
 import copy
 import gluon.contenttype
 import gluon.fileutils
+from gluon._compat import iteritems
 
 try:
     import pygraphviz as pgv
@@ -454,7 +455,7 @@ def ccache():
         except (KeyError, ZeroDivisionError):
             ram['ratio'] = 0
 
-        for key, value in cache.ram.storage.iteritems():
+        for key, value in iteritems(cache.ram.storage):
             if hp:
                 ram['bytes'] += hp.iso(value[1]).size
                 ram['objects'] += hp.iso(value[1]).count
diff --git a/gluon/compileapp.py b/gluon/compileapp.py
index b6bbda79..1a55c3bc 100644
--- a/gluon/compileapp.py
+++ b/gluon/compileapp.py
@@ -18,7 +18,7 @@ import fnmatch
 import os
 import copy
 import random
-from gluon._compat import builtin, PY2, unicodeT, to_native, basestring
+from gluon._compat import builtin, PY2, unicodeT, to_native, to_bytes, iteritems, basestring
 from gluon.storage import Storage, List
 from gluon.template import parse_template
 from gluon.restricted import restricted, compile2
@@ -395,6 +395,11 @@ _base_environment_['SQLField'] = Field  # for backward compatibility
 _base_environment_['SQLFORM'] = SQLFORM
 _base_environment_['SQLTABLE'] = SQLTABLE
 _base_environment_['LOAD'] = LOAD
+# For an easier PY3 migration
+_base_environment_['PY2'] = PY2
+_base_environment_['to_native'] = to_native
+_base_environment_['to_bytes'] = to_bytes
+_base_environment_['iteritems'] = iteritems
 
 def build_environment(request, response, session, store_current=True):
     """
diff --git a/gluon/http.py b/gluon/http.py
index a0273866..e34fb8f0 100644
--- a/gluon/http.py
+++ b/gluon/http.py
@@ -110,7 +110,7 @@ class HTTP(Exception):
         if status[:1] == '4':
             if not body:
                 body = status
-            if isinstance(body, str):
+            if isinstance(body, (str, bytes, bytearray)):
                 headers['Content-Length'] = len(body)
         rheaders = []
         for k, v in iteritems(headers):
@@ -121,7 +121,7 @@ class HTTP(Exception):
         responder(status, rheaders)
         if env.get('request_method', '') == 'HEAD':
             return ['']
-        elif isinstance(body, str):
+        elif isinstance(body, (str, bytes, bytearray)):
             return [body]
         elif hasattr(body, '__iter__'):
             return body