diff --git a/wcs_olap/wcs_api.py b/wcs_olap/wcs_api.py
index 88b76dc..0762ba8 100644
--- a/wcs_olap/wcs_api.py
+++ b/wcs_olap/wcs_api.py
@@ -75,7 +75,11 @@ class FormData(BaseObject):
         s = 0
         for evo in self.evolution[::-1]:
             if evo.status:
-                if statuses_map[evo.status].endpoint:
+                try:
+                    status = statuses_map[evo.status]
+                except KeyError:  # happen when workflow has changed
+                    return
+                if status.endpoint:
                     s = 1
                     last = evo.time - self.receipt_time
                 else: