diff --git a/cps/db.py b/cps/db.py
index a3075529..46e54706 100644
--- a/cps/db.py
+++ b/cps/db.py
@@ -352,20 +352,8 @@ class CalibreDB(threading.Thread):
             if i == 'dummy':
                 self.queue.task_done()
                 break
-            if i['task'] == 'add_format':
-                cur_book = self.session.query(Books).filter(Books.id == i['id']).first()
-                cur_book.data.append(i['format'])
-                try:
-                    # db.session.merge(cur_book)
-                    self.session.commit()
-                except OperationalError as e:
-                    self.session.rollback()
-                    self.log.error("Database error: %s", e)
-                    # self._handleError(_(u"Database error: %(error)s.", error=e))
-                    # return
             self.queue.task_done()
 
-
     def stop(self):
         self.queue.put('dummy')
 
diff --git a/cps/tasks/convert.py b/cps/tasks/convert.py
index 58b45d33..cb6d9d81 100644
--- a/cps/tasks/convert.py
+++ b/cps/tasks/convert.py
@@ -6,6 +6,8 @@ import re
 from glob import glob
 from shutil import copyfile
 
+from sqlalchemy.exc import SQLAlchemyError
+
 from cps.services.worker import CalibreTask
 from cps import calibre_db, db
 from cps import logger, config
@@ -84,9 +86,15 @@ class TaskConvert(CalibreTask):
                                          book=book_id, uncompressed_size=os.path.getsize(file_path + format_new_ext))
 
                 # todo: this may not be needed anymore, might be able to access the DB directly now. See #1565
-                task = {'task':'add_format','id': book_id, 'format': new_format}
-                self.worker_thread.db_queue.put(task)
-                # To Do how to handle error?
+                cur_book = calibre_db.session.query(db.Books).filter(db.Books.id == book_id).first()
+                cur_book.data.append(new_format)
+
+                try:
+                    # db.session.merge(cur_book)
+                    calibre_db.session.commit()
+                except SQLAlchemyError as e:
+                    calibre_db.session.rollback()
+                    log.error("Database error: %s", e)
 
                 '''cur_book.data.append(new_format)
                 try: