diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index 4c7dc353de..469f947b13 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -1695,7 +1695,10 @@ class DB(object):
     def conversion_options(self, book_id, fmt):
         for (data,) in self.conn.get('SELECT data FROM conversion_options WHERE book=? AND format=?', (book_id, fmt.upper())):
             if data:
-                return unpickle_binary_string(bytes(data))
+                try:
+                    return unpickle_binary_string(bytes(data))
+                except Exception:
+                    pass
 
     def has_conversion_options(self, ids, fmt='PIPE'):
         ids = frozenset(ids)