diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 8079ce020de..dacb47f9525 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -22,6 +22,12 @@ variables:
   - ${{ if eq(variables['System.TeamProject'], 'public') }}:
     - name: _InternalRuntimeDownloadArgs
       value: ''
+  - name: LC_ALL
+    value: 'en_US.UTF-8'
+  - name: LANG
+    value: 'en_US.UTF-8'
+  - name: LANGUAGE
+    value: 'en_US.UTF-8'
 
 trigger:
   batch: true
@@ -133,7 +139,7 @@ stages:
             timeoutInMinutes: 120
             enablePublishTestResults: true
             pool:
-              vmImage: ubuntu-16.04
+              vmImage: ubuntu-18.04
             variables:
               - _runCounter: $[counter(variables['Build.Reason'], 0)]
               - ${{ if and(eq(variables['System.TeamProject'], 'public'), eq(variables['system.pullrequest.isfork'], false), notin(variables['Build.Reason'], 'PullRequest', 'Schedule', 'BuildCompletion')) }}: