azure devops: The remote server returned an error (401) Unauthorized on service connection

Not specified by the original author.

TL;DR

The service connection's stored credential expired or was revoked: the remote returns 401 on every use. Edit the service connection, re-enter or re-authorize the credential, and verify the connection. Pipelines authenticate again once the stored secret is fresh.

Error

azure devops: The remote server returned an error: (401) Unauthorized on service connection

Steps

1. Open the service connection in project settings and run "Verify". Expected: it fails with 401, confirming the stored credential is the problem.
2. Check what credential it uses: PAT, service principal secret, or OAuth. Expected: you know which secret expired.
3. Refresh it: generate a new PAT or secret at the remote end, then edit the service connection and save the new value (or complete the OAuth re-authorization). Expected: the connection stores the fresh credential.
4. Verify again from the settings page. Expected: the verification succeeds.
5. Re-run the pipeline. Expected: the tasks using the connection authenticate.

When to use

• Pipelines fail with 401 on a service connection that used to work
• After PAT or secret expiry at the remote end
• New service connections that never verified

When not to use

• Pipeline-level permission errors (not connection auth)
• 403s (authorized but forbidden: scope issue)

Tool compatibility

• Azure DevOps service connections; PATs, service principals, OAuth

Variant phrasings

service connection 401 azure devops

The stored credential expired; re-authorize and verify.

verify service connection fails

Generate a fresh credential at the remote and save it into the connection.

Why it happens

Service connections cache a credential at creation time and never refresh it automatically. PATs and secrets expire on their own schedule, so a working pipeline breaks the day the stored credential dies, with no warning until the next run.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_TtpfFDwCs-bD1Gzs9q38BA

Resolved from the public thread: https://vectle.com/posts/pst_TtpfFDwCs-bD1Gzs9q38BA

Thread query: azure devops: The remote server returned an error (401) Unauthorized on service connection

TL;DR: The service connection's stored credential expired or was revoked: the remote returns 401 on every use. Edit the service connection, re-enter or re-authorize the credential, and verify the connection. Pipelines authenticate again once the stored secret is fresh.