diff --git a/api/command.py b/api/command.py
index 71bcd4a..e48a732 100644
--- a/api/command.py
+++ b/api/command.py
@@ -515,6 +515,7 @@ def execute_batch_command(name: str, cs: ChangeSet) -> ChangeSet:
                 r = cache_delete_command(name, ChangeSet(op))
 
             if r == None:
+                print(f'ERROR: Build [{op}] returns None')
                 return ChangeSet()
 
             if op['type'] == 'demand':