diff --git a/src/mp_api/client.py b/src/mp_api/client.py
index 77325142..62b07033 100644
--- a/src/mp_api/client.py
+++ b/src/mp_api/client.py
@@ -126,14 +126,18 @@ def __init__(
 
         try:
             self.contribs = Client(api_key)
-        except Exception:
+        except Exception as error:
             self.contribs = None
+            warnings.warn(f"Problem loading MPContribs client: {error}")
 
         self._all_resters = []
 
         if notify_db_version:
             raise NotImplementedError("This has not yet been implemented.")
 
+        if not self.endpoint.endswith("/"):
+            self.endpoint += "/"
+
         for cls in BaseRester.__subclasses__():
 
             rester = cls(