diff --git a/eng/pipelines/templates/BuildAndTest.yml b/eng/pipelines/templates/BuildAndTest.yml
index 98401edb18c..f8309057b92 100644
--- a/eng/pipelines/templates/BuildAndTest.yml
+++ b/eng/pipelines/templates/BuildAndTest.yml
@@ -167,19 +167,16 @@ steps:
               $(_OfficialBuildIdArgs)
       displayName: Pack docs transport package
 
-    - task: npmAuthenticate@0
-      inputs:
-        workingFile: $(Build.SourcesDirectory)/src/Libraries/Microsoft.Extensions.AI.Evaluation.Reporting/TypeScript/.npmrc
-      displayName: Authenticate npm for Azure DevOps plugin (root)
-
-    - task: npmAuthenticate@0
-      inputs:
-        workingFile: $(Build.SourcesDirectory)/src/Libraries/Microsoft.Extensions.AI.Evaluation.Reporting/TypeScript/azure-devops-report/tasks/PublishAIEvaluationReport/.npmrc
-      displayName: Authenticate npm for Azure DevOps plugin (task)
-
     - pwsh: |
           $(Build.SourcesDirectory)/src/Libraries/Microsoft.Extensions.AI.Evaluation.Reporting/TypeScript/azure-devops-report/build.ps1 -OutputPath $(Build.Arcade.VSIXOutputPath)
       displayName: Build Azure DevOps plugin
+      env:
+        # Some CI agents have stale npm auth tokens in the user-level .npmrc
+        # (e.g. C:\Users\cloudtest\.npmrc). npm sends these stale credentials
+        # to the public dotnet-public-npm feed, causing E401 errors. Override
+        # the user config path to a non-existent file so npm ignores stale
+        # credentials and uses anonymous access for the public feed.
+        NPM_CONFIG_USERCONFIG: $(Agent.TempDirectory)/.npmrc-not-exists
 
     - script: ${{ parameters.buildScript }}
               -restore