diff --git a/swh/storage/converters.py b/swh/storage/converters.py
--- a/swh/storage/converters.py
+++ b/swh/storage/converters.py
@@ -83,7 +83,7 @@
 
 
 def db_to_date(
-    date: Optional[datetime.datetime], offset: int, neg_utc_offset: bool
+    date: Optional[datetime.datetime], offset: int, neg_utc_offset: Optional[bool]
 ) -> Optional[TimestampWithTimezone]:
     """Convert the DB representation of a date to a swh-model compatible date.
 
@@ -100,6 +100,10 @@
     if date is None:
         return None
 
+    if neg_utc_offset is None:
+        # For older versions of the database that were not migrated to schema v160
+        neg_utc_offset = False
+
     return TimestampWithTimezone(
         timestamp=Timestamp(
             seconds=int(date.timestamp()), microseconds=date.microsecond,