diff --git a/archivebox/index.py b/archivebox/index.py
index 74e7dd42..eab2197b 100644
--- a/archivebox/index.py
+++ b/archivebox/index.py
@@ -120,12 +120,18 @@ def write_json_links_index(out_dir: str, links: List[Link]) -> None:
 def parse_json_links_index(out_dir: str=OUTPUT_DIR) -> Iterator[Link]:
     """parse a archive index json file and return the list of links"""
 
+    allowed_fields = {f.name for f in fields(Link)}
+
     index_path = os.path.join(out_dir, 'index.json')
     if os.path.exists(index_path):
         with open(index_path, 'r', encoding='utf-8') as f:
             links = json.load(f)['links']
-            for link in links:
-                yield Link(**link)
+            for link_json in links:
+                yield Link(**{
+                    key: val
+                    for key, val in link_json.items()
+                    if key in allowed_fields
+                })
 
     return ()
 
diff --git a/archivebox/schema.py b/archivebox/schema.py
index 434f9dc5..5aa629d7 100644
--- a/archivebox/schema.py
+++ b/archivebox/schema.py
@@ -164,7 +164,7 @@ class Link:
         from util import ts_to_date
 
         most_recent = min(
-            (result.start_ts
+            (ts_to_date(result.start_ts)
              for method in self.history.keys()
                 for result in self.history[method]),
             default=None,
@@ -176,7 +176,7 @@ class Link:
         from util import ts_to_date
 
         most_recent = max(
-            (result.start_ts
+            (ts_to_date(result.start_ts)
              for method in self.history.keys()
                 for result in self.history[method]),
             default=None,