diff --git a/docs/redmine_issue.py b/docs/redmine_issue.py
index 35c3b12..0df2b1f 100644
--- a/docs/redmine_issue.py
+++ b/docs/redmine_issue.py
@@ -50,8 +50,8 @@
         base = app.config.redmine_project_url
         if not base:
             raise AttributeError
-    except AttributeError, err:
-        raise ValueError('redmine_project_url configuration value is not set (%s)' % str(err))
+    except AttributeError:
+        raise ValueError('redmine_project_url configuration value is not set')
     #
     slash = '/' if base[-1] != '/' else ''
     ref = base + slash + type + '/' + slug + '/'