Closes #12906: Fixed bug in YAML configuration.
diff --git a/Doc/howto/logging.rst b/Doc/howto/logging.rst
index 5ff0d74..2c9514a 100644
--- a/Doc/howto/logging.rst
+++ b/Doc/howto/logging.rst
@@ -679,7 +679,7 @@
     version: 1
     formatters:
       simple:
-        format: format=%(asctime)s - %(name)s - %(levelname)s - %(message)s
+        format: '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
     handlers:
       console:
         class: logging.StreamHandler