diff --git a/pygeometa/pygeoapi_plugin.py b/pygeometa/pygeoapi_plugin.py
index 732d370..118484e 100644
--- a/pygeometa/pygeoapi_plugin.py
+++ b/pygeometa/pygeoapi_plugin.py
@@ -384,7 +384,7 @@ def __init__(self, processor_def):
 
         super().__init__(processor_def, PROCESS_METADATA_IMPORT)
 
-    def execute(self, data):
+    def execute(self, data, outputs=None):
 
         response = None
         mimetype = 'application/json'
@@ -433,7 +433,7 @@ def __init__(self, processor_def):
 
         super().__init__(processor_def, PROCESS_METADATA_VALIDATE)
 
-    def execute(self, data):
+    def execute(self, data, outputs=None):
 
         response = None
         mimetype = 'application/json'
@@ -477,7 +477,7 @@ def __init__(self, processor_def):
 
         super().__init__(processor_def, PROCESS_METADATA_GENERATE)
 
-    def execute(self, data):
+    def execute(self, data, outputs=None):
 
         response = None
         mimetype = 'application/json'
@@ -525,7 +525,7 @@ def __init__(self, processor_def):
 
         super().__init__(processor_def, PROCESS_METADATA_TRANSFORM)
 
-    def execute(self, data):
+    def execute(self, data, outputs=None):
 
         content = None
         response = None