Fix format string error

Change-Id: I2657a311d7ffe4e6e8110f60d3bc9b474672cd1a

1 files changed, 1 insertions, 1 deletions

diff --git a/util.py b/util.py
index ce41f0c..8321ed9 100644
--- a/util.py
+++ b/util.py
@@ -281,7 +281,7 @@ class VlanUtil:
                     del s
 
                 except IOError as e:
-                    logging.error('Failed to add VLAN %d to switch ID %d (%s): %s', tag, switch.switch_id, switch.name)
+                    logging.error('Failed to add VLAN %d to switch ID %d (%s): %s', tag, switch.switch_id, switch.name, e)
                     raise
 
         except IOError: