diff --git a/frappe/core/doctype/file_data/file_data.py b/frappe/core/doctype/file_data/file_data.py
index a457a3da5b..4d88a6adca 100644
--- a/frappe/core/doctype/file_data/file_data.py
+++ b/frappe/core/doctype/file_data/file_data.py
@@ -44,8 +44,8 @@ class FileData(Document):
 				pass
 
 		# if file not attached to any other record, delete it
-		if self.file_name and not frappe.db.count("File Data", 
-			{"content_hash": self.content_hash, "name": ["!=", self.name]}):
+		if self.file_name and self.content_hash and (not frappe.db.count("File Data",
+			{"content_hash": self.content_hash, "name": ["!=", self.name]})):
 				delete_file_data_content(self)
 
 	def on_rollback(self):
diff --git a/frappe/patches/4_0/file_manager_hooks.py b/frappe/patches/4_0/file_manager_hooks.py
index 5c72e62da3..ef043d4d31 100644
--- a/frappe/patches/4_0/file_manager_hooks.py
+++ b/frappe/patches/4_0/file_manager_hooks.py
@@ -21,7 +21,16 @@ def execute():
 			b.file_url = os.path.normpath('/' + old_file_name)
 		else:
 			b.file_url = os.path.normpath('/files/' + old_file_name)
-		_file_name, content = get_file(name)
-		b.content_hash = get_content_hash(content)
-		b.save()
+		try:
+			_file_name, content = get_file(name)
+			b.content_hash = get_content_hash(content)
+		except IOError:
+			print 'Warning: Error processing ', name
+			_file_name = old_file_name
+			b.content_hash = None
+
+		try:
+			b.save()
+		except frappe.DuplicateEntryError:
+			frappe.delete_doc(b.doctype, b.name)