diff --git a/beat/backend/python/data.py b/beat/backend/python/data.py
index 0af51df6d48d0655cfc885c6441d70a38701bfc2..13adf7a201823705315b3d28cffe0e2ebb694164 100644
--- a/beat/backend/python/data.py
+++ b/beat/backend/python/data.py
@@ -935,8 +935,15 @@ class CachedDataSink(DataSink):
 
         try:
             self.data_file = open(self.filename, "wb")
-            self.index_file = open(self.filename.replace(".data", ".index"), "wt")
-        except Exception:
+        except Exception as e:
+            logger.error("Failed to open data file {}: {}".format(self.filename, e))
+            return False
+
+        try:
+            index_filename = self.filename.replace(".data", ".index")
+            self.index_file = open(index_filename, "wt")
+        except Exception as e:
+            logger.error("Failed to open index file {}: {}".format(index_filename, e))
             return False
 
         # Write the dataformat