diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 3281f54c37d..9e7825f03b9 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -221,7 +221,7 @@ stages:
             maxParallel: 2
             matrix:
               regular:
-                _experimental_flag: null
+                _experimental_flag: ''
               experimental_features:
                 _experimental_flag: 1
           steps:
@@ -479,7 +479,7 @@ stages:
             maxParallel: 2
             matrix:
               regular:
-                _experimental_flag: null
+                _experimental_flag: ''
               experimental_features:
                 _experimental_flag: 1
           steps: