diff --git a/sat/tools/common/template.py b/sat/tools/common/template.py
index 6790a350..cc797552 100644
--- a/sat/tools/common/template.py
+++ b/sat/tools/common/template.py
@@ -454,7 +454,7 @@ class Renderer(object):
         self.env.policies["json.dumps_kwargs"] = {
             "sort_keys": True,
             # if object can't be serialised, we use None
-            "default": lambda o: o.json() if hasattr(o, "json") else None
+            "default": lambda o: o.to_json() if hasattr(o, "to_json") else None
         }
 
     def getFrontURL(self, template_data, path=None):
@@ -734,8 +734,8 @@ class Renderer(object):
         current = ctx["gidx"].current(value)
         return value if not current else "{}_{}".format(value, current)
 
-    def _date_fmt(self, timestamp, fmt="short", date_only=False, auto_limit=None,
-                  auto_old_fmt=None):
+    def _date_fmt(self, timestamp, fmt="short", date_only=False, auto_limit=7,
+                  auto_old_fmt="short", auto_new_fmt="relative"):
         if is_undefined(fmt):
             fmt = "short"
         try: