diff --git a/mayan/apps/common/managers.py b/mayan/apps/common/managers.py
index c99c8f631d..9dbcbe97d4 100644
--- a/mayan/apps/common/managers.py
+++ b/mayan/apps/common/managers.py
@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 from django.apps import apps
+from django.contrib.auth import get_user_model
 from django.contrib.contenttypes.fields import GenericRelation
 from django.db import models
 
@@ -11,3 +12,14 @@ class ErrorLogEntryManager(models.Manager):
             app_label='common', model_name='ErrorLogEntry'
         )
         model.add_to_class('error_logs', GenericRelation(ErrorLogEntry))
+
+
+class UserLocaleProfileManager(models.Manager):
+    def get_by_natural_key(self, user_natural_key):
+        User = get_user_model()
+        try:
+            user = User.objects.get_by_natural_key(user_natural_key)
+        except User.DoesNotExist:
+            raise self.model.DoesNotExist
+
+        return self.get(user__pk=user.pk)
diff --git a/mayan/apps/common/models.py b/mayan/apps/common/models.py
index 298f1dba0b..2bcc9232c0 100644
--- a/mayan/apps/common/models.py
+++ b/mayan/apps/common/models.py
@@ -11,7 +11,7 @@ from django.db import models
 from django.utils.encoding import force_text, python_2_unicode_compatible
 from django.utils.translation import ugettext_lazy as _
 
-from .managers import ErrorLogEntryManager
+from .managers import ErrorLogEntryManager, UserLocaleProfileManager
 from .storages import storage_sharedupload
 
 
@@ -88,9 +88,16 @@ class UserLocaleProfile(models.Model):
         choices=settings.LANGUAGES, max_length=8, verbose_name=_('Language')
     )
 
+    objects = UserLocaleProfileManager()
+
     class Meta:
         verbose_name = _('User locale profile')
         verbose_name_plural = _('User locale profiles')
 
     def __str__(self):
         return force_text(self.user)
+
+    def natural_key(self):
+        return self.user.natural_key()
+    natural_key.dependencies = [settings.AUTH_USER_MODEL]
+
diff --git a/mayan/apps/documents/managers.py b/mayan/apps/documents/managers.py
index d6d3dc7946..5efb8d9f80 100644
--- a/mayan/apps/documents/managers.py
+++ b/mayan/apps/documents/managers.py
@@ -6,6 +6,7 @@ import logging
 from django.apps import apps
 from django.db import models
 from django.db.models import F, Max
+from django.utils.encoding import force_text
 from django.utils.timezone import now
 
 from .literals import STUB_EXPIRATION_INTERVAL
@@ -20,7 +21,7 @@ class DocumentManager(models.Manager):
             stale_stub_document.delete(trash=False)
 
     def get_by_natural_key(self, uuid):
-        return self.model.passthrough.get(uuid=uuid)
+        return self.model.passthrough.get(uuid=force_text(uuid))
 
     def get_queryset(self):
         return TrashCanQuerySet(
@@ -33,7 +34,7 @@ class DocumentManager(models.Manager):
 
 
 class DocumentVersionManager(models.Manager):
-    def get_by_natural_key(self, checksum, document_natural_key):
+    def get_by_natural_key(self, document_natural_key, checksum):
         Document = apps.get_model(
             app_label='documents', model_name='Document'
         )
diff --git a/mayan/apps/documents/models.py b/mayan/apps/documents/models.py
index f98afd2b5f..370cbd0ada 100644
--- a/mayan/apps/documents/models.py
+++ b/mayan/apps/documents/models.py
@@ -509,7 +509,7 @@ class DocumentVersion(models.Model):
         )
 
     def natural_key(self):
-        return (self.checksum,) + self.document.natural_key()
+        return self.document.natural_key() + (self.checksum,)
     natural_key.dependencies = ['documents.Document']
 
     def invalidate_cache(self):
diff --git a/mayan/apps/metadata/managers.py b/mayan/apps/metadata/managers.py
index 2a07fc459a..76f8830d19 100644
--- a/mayan/apps/metadata/managers.py
+++ b/mayan/apps/metadata/managers.py
@@ -24,16 +24,24 @@ class MetadataTypeManager(models.Manager):
 
 
 class DocumentTypeMetadataTypeManager(models.Manager):
-    def get_by_natural_key(self, metadata_type_name, document_natural_key):
+    def get_by_natural_key(self, document_natural_key, metadata_type_natural_key):
         Document = apps.get_model(
             app_label='documents', model_name='Document'
         )
+        MetadataType = apps.get_model(
+            app_label='metadata', model_name='MetadataType'
+        )
         try:
             document = Document.objects.get_by_natural_key(document_natural_key)
         except Document.DoesNotExist:
             raise self.model.DoesNotExist
+        else:
+            try:
+                metadata_type = MetadataType.objects.get_by_natural_key(metadata_type_natural_key)
+            except MetadataType.DoesNotExist:
+                raise self.model.DoesNotExist
 
-        return document.metadata.get(metadata_type_name=metadata_type_name)
+        return self.get(document__pk=document.pk, metadata_type__pk=metadata_type.pk)
 
     def get_metadata_types_for(self, document_type):
         DocumentType = apps.get_model(
diff --git a/mayan/apps/metadata/models.py b/mayan/apps/metadata/models.py
index 89d312d1b0..be67f0093b 100644
--- a/mayan/apps/metadata/models.py
+++ b/mayan/apps/metadata/models.py
@@ -111,7 +111,7 @@ class MetadataType(models.Model):
         ).exists()
 
     def natural_key(self):
-        return self.name
+        return (self.name,)
 
     def validate_value(self, document_type, value):
         # Check default
@@ -190,7 +190,7 @@ class DocumentMetadata(models.Model):
         return super(DocumentMetadata, self).delete(*args, **kwargs)
 
     def natural_key(self):
-        return (self.metadata_type.name,) + self.document.natural_key()
+        return self.document.natural_key() + self.metadata_type.natural_key()
     natural_key.dependencies = ['documents.Document', 'metadata.MetadataType']
 
     @property
diff --git a/mayan/apps/ocr/managers.py b/mayan/apps/ocr/managers.py
index 20de7b30b6..c6723e1926 100644
--- a/mayan/apps/ocr/managers.py
+++ b/mayan/apps/ocr/managers.py
@@ -102,4 +102,4 @@ class DocumentTypeSettingsManager(models.Manager):
         except DocumentType.DoesNotExist:
             raise self.model.DoesNotExist
 
-        return document_type.ocr_settings
+        return self.get(document_type__pk=document_type.pk)