diff --git a/apps/lock_manager/managers.py b/apps/lock_manager/managers.py
index 603a36c575..99145e8c5a 100644
--- a/apps/lock_manager/managers.py
+++ b/apps/lock_manager/managers.py
@@ -22,6 +22,7 @@ class LockManager(models.Manager):
             logger.debug('acquired lock: %s' % name)
             return lock
         except IntegrityError, msg:
+            transaction.rollback()
             logger.debug('IntegrityError: %s', msg)
             # There is already an existing lock
             # Check it's expiration date and if expired, reset it
diff --git a/apps/ocr/__init__.py b/apps/ocr/__init__.py
index 5f160d4fce..c1c280503c 100644
--- a/apps/ocr/__init__.py
+++ b/apps/ocr/__init__.py
@@ -7,6 +7,7 @@ from django.utils.translation import ugettext_lazy as _
 from django.utils.translation import ugettext
 from django.db.models.signals import post_save, post_syncdb
 from django.dispatch import receiver
+from django.db.utils import DatabaseError
 
 from navigation.api import register_links, register_multi_item_links
 from documents.models import Document, DocumentVersion
@@ -64,10 +65,14 @@ register_maintenance_links([all_document_ocr_cleanup], namespace='ocr', title=_(
 
 @transaction.commit_on_success
 def create_default_queue():
-    default_queue, created = DocumentQueue.objects.get_or_create(name='default')
-    if created:
-        default_queue.label = ugettext(u'Default')
-        default_queue.save()
+    try:
+        default_queue, created = DocumentQueue.objects.get_or_create(name='default')
+    except DatabaseError:
+        transaction.rollback()
+    else:
+        if created:
+            default_queue.label = ugettext(u'Default')
+            default_queue.save()
 
 
 @receiver(post_save, dispatch_uid='document_post_save', sender=DocumentVersion)
diff --git a/apps/sources/models.py b/apps/sources/models.py
index 6fb3ca3f67..5e32cddb7a 100644
--- a/apps/sources/models.py
+++ b/apps/sources/models.py
@@ -9,6 +9,7 @@ from django.contrib.contenttypes.models import ContentType
 from django.contrib.contenttypes import generic
 from django.core.exceptions import ValidationError
 from django.db import transaction
+from django.db.utils import DatabaseError
 
 from converter.api import get_available_transformations_choices
 from converter.literals import DIMENSION_SEPARATOR
@@ -93,7 +94,7 @@ class BaseModel(models.Model):
             document = Document()
             if document_type:
                 document.document_type = document_type
-            document.save()
+                document.save()
 
             apply_default_acls(document, user)
  
@@ -119,7 +120,8 @@ class BaseModel(models.Model):
             new_version = document.new_version(file=file_object, **new_version_data)
         except Exception:
             # Don't leave the database in a broken state
-            document.delete()
+            # document.delete()
+            transaction.rollback()
             raise
             
         if filename: