diff --git a/cps/gdrive.py b/cps/gdrive.py
index 584c90cf..8f8b9aa8 100644
--- a/cps/gdrive.py
+++ b/cps/gdrive.py
@@ -84,6 +84,7 @@ def watch_gdrive():
     if not config.config_google_drive_watch_changes_response:
         with open(gdriveutils.CLIENT_SECRETS, 'r') as settings:
             filedata = json.load(settings)
+        # ToDo: Easier: rstrip('/')
         if filedata['web']['redirect_uris'][0].endswith('/'):
             filedata['web']['redirect_uris'][0] = filedata['web']['redirect_uris'][0][:-((len('/gdrive/callback')+1))]
         else:
@@ -123,6 +124,8 @@ def revoke_watch_gdrive():
 
 @gdrive.route("/gdrive/watch/callback", methods=['GET', 'POST'])
 def on_received_watch_confirmation():
+    if not config.config_google_drive_watch_changes_response:
+        return ''
     if request.headers.get('X-Goog-Channel-Token') != gdrive_watch_callback_token \
             or request.headers.get('X-Goog-Resource-State') != 'change' \
             or not request.data:
diff --git a/cps/services/worker.py b/cps/services/worker.py
index c2ea594c..7018a05a 100644
--- a/cps/services/worker.py
+++ b/cps/services/worker.py
@@ -110,7 +110,7 @@ class WorkerThread(threading.Thread):
                 # We don't use a daemon here because we don't want the tasks to just be abruptly halted, leading to
                 # possible file / database corruption
                 item = self.queue.get(timeout=1)
-            except queue.Empty as ex:
+            except queue.Empty:
                 time.sleep(1)
                 continue
 
diff --git a/cps/tasks/convert.py b/cps/tasks/convert.py
index 5e38b8ef..39d42dcd 100644
--- a/cps/tasks/convert.py
+++ b/cps/tasks/convert.py
@@ -80,10 +80,11 @@ class TaskConvert(CalibreTask):
         format_old_ext = u'.' + self.settings['old_book_format'].lower()
         format_new_ext = u'.' + self.settings['new_book_format'].lower()
 
-        # check to see if destination format already exists -
+        # check to see if destination format already exists - or if book is in database
         # if it does - mark the conversion task as complete and return a success
         # this will allow send to kindle workflow to continue to work
-        if os.path.isfile(file_path + format_new_ext):
+        if os.path.isfile(file_path + format_new_ext) or\
+            local_db.get_book_format(self.bookid, self.settings['new_book_format']):
             log.info("Book id %d already converted to %s", book_id, format_new_ext)
             cur_book = local_db.get_book(book_id)
             self.results['path'] = file_path
@@ -111,7 +112,7 @@ class TaskConvert(CalibreTask):
         if check == 0:
             cur_book = local_db.get_book(book_id)
             if os.path.isfile(file_path + format_new_ext):
-                # self.db_queue.join()
+                # check if format is already there and replace it if so, problem with gdrive kepub upload (why?)
                 new_format = db.Data(name=cur_book.data[0].name,
                                          book_format=self.settings['new_book_format'].upper(),
                                          book=book_id, uncompressed_size=os.path.getsize(file_path + format_new_ext))
@@ -119,7 +120,7 @@ class TaskConvert(CalibreTask):
                     local_db.session.merge(new_format)
                     local_db.session.commit()
                 except SQLAlchemyError as e:
-                    local_db.rollback()
+                    local_db.session.rollback()
                     log.error("Database error: %s", e)
                     local_db.session.close()
                     return