diff --git a/etc/ironic/ironic.conf.sample b/etc/ironic/ironic.conf.sample
index 86cc062be7..ab0d663541 100644
--- a/etc/ironic/ironic.conf.sample
+++ b/etc/ironic/ironic.conf.sample
@@ -663,7 +663,7 @@
 # be done on any GET or POST requests if this is set to
 # "GET,POST". It is used only when API audit is enabled.
 # (string value)
-#ignore_req_list = <None>
+#ignore_req_list =
 
 
 [cimc]
diff --git a/ironic/conf/audit.py b/ironic/conf/audit.py
index 784e588362..d71b340f57 100644
--- a/ironic/conf/audit.py
+++ b/ironic/conf/audit.py
@@ -26,6 +26,7 @@ opts = [
                       'Used only when API audit is enabled.')),
 
     cfg.StrOpt('ignore_req_list',
+               default='',
                help=_('Comma separated list of Ironic REST API HTTP methods '
                       'to be ignored during audit logging. For example: '
                       'auditing will not be done on any GET or POST '
diff --git a/releasenotes/notes/bug-1648387-92db52cbe007fabd.yaml b/releasenotes/notes/bug-1648387-92db52cbe007fabd.yaml
new file mode 100644
index 0000000000..9d3ba1b1b2
--- /dev/null
+++ b/releasenotes/notes/bug-1648387-92db52cbe007fabd.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - Fixes the issue that API service does not start if audit is enabled with
+    default value of "ignore_req_list" config option.