diff --git a/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py b/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py
--- a/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py
+++ b/rhodecode/lib/dbmigrate/migrate/changeset/ansisql.py
@@ -4,7 +4,7 @@
    At the moment, this isn't so much based off of ANSI as much as
    things that just happen to work with multiple databases.
 """
-from io import StringIO
+import io
 
 import sqlalchemy as sa
 from sqlalchemy.schema import SchemaVisitor
@@ -48,7 +48,7 @@ class AlterTableVisitor(SchemaVisitor):
 
     def __init__(self, dialect, connection, **kw):
         self.connection = connection
-        self.buffer = StringIO.StringIO()
+        self.buffer = io.StringIO()
         self.preparer = dialect.identifier_preparer
         self.dialect = dialect
 
@@ -205,7 +205,7 @@ class ANSISchemaChanger(AlterTableVisito
     def visit_column(self, delta):
         """Rename/change a column."""
         # ALTER COLUMN is implemented as several ALTER statements
-        keys = delta.keys()
+        keys = list(delta.keys())
         if 'type' in keys:
             self._run_subvisit(delta, self._visit_column_type)
         if 'nullable' in keys:
diff --git a/rhodecode/lib/dbmigrate/migrate/changeset/constraint.py b/rhodecode/lib/dbmigrate/migrate/changeset/constraint.py
--- a/rhodecode/lib/dbmigrate/migrate/changeset/constraint.py
+++ b/rhodecode/lib/dbmigrate/migrate/changeset/constraint.py
@@ -128,7 +128,7 @@ class ForeignKeyConstraint(ConstraintCha
         """Mimic the database's automatic constraint names"""
         if hasattr(self.columns, 'keys'):
             # SA <= 0.5
-            firstcol = self.columns[self.columns.keys()[0]]
+            firstcol = self.columns[list(self.columns.keys())[0]]
             ret = "%(table)s_%(firstcolumn)s_fkey" % {
                 'table': firstcol.table.name,
                 'firstcolumn': firstcol.name,}
diff --git a/rhodecode/lib/dbmigrate/migrate/changeset/databases/oracle.py b/rhodecode/lib/dbmigrate/migrate/changeset/databases/oracle.py
--- a/rhodecode/lib/dbmigrate/migrate/changeset/databases/oracle.py
+++ b/rhodecode/lib/dbmigrate/migrate/changeset/databases/oracle.py
@@ -34,7 +34,7 @@ class OracleSchemaChanger(OracleSchemaGe
         return ret
 
     def visit_column(self, delta):
-        keys = delta.keys()
+        keys = list(delta.keys())
 
         if 'name' in keys:
             self._run_subvisit(delta,
@@ -51,15 +51,15 @@ class OracleSchemaChanger(OracleSchemaGe
         # to null.  We'll do that if default=None
         # http://forums.oracle.com/forums/message.jspa?messageID=1273234#1273234
         dropdefault_hack = (column.server_default is None \
-                                and 'server_default' in delta.keys())
+                                and 'server_default' in list(delta.keys()))
         # Oracle apparently doesn't like it when we say "not null" if
         # the column's already not null. Fudge it, so we don't need a
         # new function
         notnull_hack = ((not column.nullable) \
-                            and ('nullable' not in delta.keys()))
+                            and ('nullable' not in list(delta.keys())))
         # We need to specify NULL if we're removing a NOT NULL
         # constraint
-        null_hack = (column.nullable and ('nullable' in delta.keys()))
+        null_hack = (column.nullable and ('nullable' in list(delta.keys())))
 
         if dropdefault_hack:
             column.server_default = sa.PassiveDefault(sa.sql.null())
diff --git a/rhodecode/lib/dbmigrate/migrate/changeset/schema.py b/rhodecode/lib/dbmigrate/migrate/changeset/schema.py
--- a/rhodecode/lib/dbmigrate/migrate/changeset/schema.py
+++ b/rhodecode/lib/dbmigrate/migrate/changeset/schema.py
@@ -245,12 +245,12 @@ class ColumnDelta(DictMixin, sqlalchemy.
             )
 
     def __getitem__(self, key):
-        if key not in self.keys():
+        if key not in list(self.keys()):
             raise KeyError("No such diff key, available: %s" % self.diffs )
         return getattr(self.result_column, key)
 
     def __setitem__(self, key, value):
-        if key not in self.keys():
+        if key not in list(self.keys()):
             raise KeyError("No such diff key, available: %s" % self.diffs )
         setattr(self.result_column, key, value)
 
@@ -264,7 +264,7 @@ class ColumnDelta(DictMixin, sqlalchemy.
         raise NotImplementedError
 
     def keys(self):
-        return self.diffs.keys()
+        return list(self.diffs.keys())
 
     def compare_parameters(self, current_name, *p, **k):
         """Compares Column objects with reflection"""
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/api.py b/rhodecode/lib/dbmigrate/migrate/versioning/api.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/api.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/api.py
@@ -58,7 +58,7 @@ command_desc = {
     'make_update_script_for_model': 'create a script changing the old MetaData to the new (current) MetaData',
     'update_db_from_model': 'modify the database to match the structure of the current MetaData',
 }
-__all__ = command_desc.keys()
+__all__ = list(command_desc.keys())
 
 Repository = repository.Repository
 ControlledSchema = schema.ControlledSchema
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/genmodel.py b/rhodecode/lib/dbmigrate/migrate/versioning/genmodel.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/genmodel.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/genmodel.py
@@ -192,7 +192,7 @@ class ModelGenerator(object):
             downgradeCommands.append(
                 "post_meta.tables[%(table)r].drop()" % {'table': tn})
 
-        for (tn, td) in self.diff.tables_different.items():
+        for (tn, td) in list(self.diff.tables_different.items()):
             if td.columns_missing_from_A or td.columns_different:
                 pre_table = self.diff.metadataB.tables[tn]
                 decls.extend(self._getTableDefn(
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/migrate_repository.py b/rhodecode/lib/dbmigrate/migrate/versioning/migrate_repository.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/migrate_repository.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/migrate_repository.py
@@ -13,12 +13,12 @@ log = logging.getLogger(__name__)
 
 def usage():
     """Gives usage information."""
-    print("""Usage: %(prog)s repository-to-migrate
+    print(("""Usage: %(prog)s repository-to-migrate
 
     Upgrade your repository to the new flat format.
 
     NOTE: You should probably make a backup before running this.
-    """ % {'prog': sys.argv[0]})
+    """ % {'prog': sys.argv[0]}))
 
     sys.exit(1)
 
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/repository.py b/rhodecode/lib/dbmigrate/migrate/versioning/repository.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/repository.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/repository.py
@@ -37,22 +37,22 @@ class Changeset(dict):
             self.add(change)
 
     def __iter__(self):
-        return iter(self.items())
+        return iter(list(self.items()))
 
     def keys(self):
         """
         In a series of upgrades x -> y, keys are version x. Sorted.
         """
-        ret = super(Changeset, self).keys()
+        ret = list(super(Changeset, self).keys())
         # Reverse order if downgrading
         ret.sort(reverse=(self.step < 1))
         return ret
 
     def values(self):
-        return [self[k] for k in self.keys()]
+        return [self[k] for k in list(self.keys())]
 
     def items(self):
-        return zip(self.keys(), self.values())
+        return list(zip(list(self.keys()), list(self.values())))
 
     def add(self, change):
         """Add new change to changeset"""
@@ -221,7 +221,7 @@ class Repository(pathed.Pathed):
             range_mod = 0
             op = 'downgrade'
 
-        versions = range(int(start) + range_mod, int(end) + range_mod, step)
+        versions = list(range(int(start) + range_mod, int(end) + range_mod, step))
         changes = [self.version(v).script(database, op) for v in versions]
         ret = Changeset(start, step=step, *changes)
         return ret
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/schema.py b/rhodecode/lib/dbmigrate/migrate/versioning/schema.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/schema.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/schema.py
@@ -50,7 +50,7 @@ class ControlledSchema(object):
             data = list(result)[0]
         except:
             cls, exc, tb = sys.exc_info()
-            raise exceptions.DatabaseNotControlledError, exc.__str__(), tb
+            raise exceptions.DatabaseNotControlledError(exc.__str__()).with_traceback(tb)
 
         self.version = data['version']
         return data
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/schemadiff.py b/rhodecode/lib/dbmigrate/migrate/versioning/schemadiff.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/schemadiff.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/schemadiff.py
@@ -97,7 +97,7 @@ class ColDiff(object):
                 self.diff=True
                 return
 
-    def __nonzero__(self):
+    def __bool__(self):
         return self.diff
 
     __bool__ = __nonzero__
@@ -132,7 +132,7 @@ class TableDiff(object):
         'columns_different',
         )
 
-    def __nonzero__(self):
+    def __bool__(self):
         return bool(
             self.columns_missing_from_A or
             self.columns_missing_from_B or
@@ -277,7 +277,7 @@ class SchemaDiff(object):
                             label,', '.join(sorted(names))
                             )
                         )
-            for name,cd in td.columns_different.items():
+            for name,cd in list(td.columns_different.items()):
                 out.append('    column with differences: %s' % name)
                 out.append(column_template % (self.labelA,cd.col_A))
                 out.append(column_template % (self.labelB,cd.col_B))
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/shell.py b/rhodecode/lib/dbmigrate/migrate/versioning/shell.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/shell.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/shell.py
@@ -23,7 +23,7 @@ alias = {
 
 def alias_setup():
     global alias
-    for key, val in alias.items():
+    for key, val in list(alias.items()):
         setattr(api, key, val)
 alias_setup()
 
@@ -135,7 +135,7 @@ def main(argv=None, **kwargs):
             override_kwargs[opt] = value
 
     # override kwargs with options if user is overwriting
-    for key, value in options.__dict__.items():
+    for key, value in list(options.__dict__.items()):
         if value is not None:
             override_kwargs[key] = value
 
@@ -143,7 +143,7 @@ def main(argv=None, **kwargs):
     f_required = list(f_args)
     candidates = dict(kwargs)
     candidates.update(override_kwargs)
-    for key, value in candidates.items():
+    for key, value in list(candidates.items()):
         if key in f_args:
             f_required.remove(key)
 
@@ -160,7 +160,7 @@ def main(argv=None, **kwargs):
     kwargs.update(override_kwargs)
 
     # configure options
-    for key, value in options.__dict__.items():
+    for key, value in list(options.__dict__.items()):
         kwargs.setdefault(key, value)
 
     # configure logging
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/util/__init__.py b/rhodecode/lib/dbmigrate/migrate/versioning/util/__init__.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/util/__init__.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/util/__init__.py
@@ -131,7 +131,7 @@ def construct_engine(engine, **opts):
         kwargs['echo'] = echo
 
     # parse keyword arguments
-    for key, value in opts.items():
+    for key, value in list(opts.items()):
         if key.startswith('engine_arg_'):
             kwargs[key[11:]] = guess_obj_type(value)
 
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/util/importpath.py b/rhodecode/lib/dbmigrate/migrate/versioning/util/importpath.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/util/importpath.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/util/importpath.py
@@ -1,5 +1,6 @@
 import os
 import sys
+import importlib
 
 def import_path(fullpath):
     """ Import a file with full path specification. Allows one to
@@ -10,6 +11,6 @@ def import_path(fullpath):
     filename, ext = os.path.splitext(filename)
     sys.path.append(path)
     module = __import__(filename)
-    reload(module) # Might be out of date during tests
+    importlib.reload(module) # Might be out of date during tests
     del sys.path[-1]
     return module
diff --git a/rhodecode/lib/dbmigrate/migrate/versioning/version.py b/rhodecode/lib/dbmigrate/migrate/versioning/version.py
--- a/rhodecode/lib/dbmigrate/migrate/versioning/version.py
+++ b/rhodecode/lib/dbmigrate/migrate/versioning/version.py
@@ -96,13 +96,13 @@ class Collection(pathed.Pathed):
         # Create the versions member where the keys
         # are VerNum's and the values are Version's.
         self.versions = {}
-        for num, files in tempVersions.items():
+        for num, files in list(tempVersions.items()):
             self.versions[VerNum(num)] = Version(num, path, files)
 
     @property
     def latest(self):
         """:returns: Latest version in Collection"""
-        return max([VerNum(0)] + self.versions.keys())
+        return max([VerNum(0)] + list(self.versions.keys()))
 
     def _next_ver_num(self, use_timestamp_numbering):
         if use_timestamp_numbering == True: