Fixed log message.

Change-Id: I1d6dcee6284399cdb30a40c4d2e7557ee0c7fee1
diff --git a/utils/misc/src/main/java/org/onlab/util/AbstractAccumulator.java b/utils/misc/src/main/java/org/onlab/util/AbstractAccumulator.java
index 3aa4509..500f8d6 100644
--- a/utils/misc/src/main/java/org/onlab/util/AbstractAccumulator.java
+++ b/utils/misc/src/main/java/org/onlab/util/AbstractAccumulator.java
@@ -150,7 +150,7 @@
                         processItems(batch);
                     }
                 } catch (Exception e) {
-                    log.warn("Unable to process batch due to {}", e);
+                    log.warn("Unable to process batch due to", e);
                 }
             } else {
                 synchronized (AbstractAccumulator.this) {