auth token refresh failed when agent tried to re-auth the defender API

TL;DR

Refresh failures have their own causes distinct from login failures: the stored refresh material was rotated or revoked, the app lost a permission it previously held, or the identity provider changed policy, such as requiring interaction after a risk event. Read the exact error code from the provider, since it distinguishes expired, revoked and policy-blocked refresh, and act on that class rather than retrying the same refresh harder.

auth token refresh failed when agent tried to re-auth the defender API

Use this when

• The agent works until its first refresh, then loses API access.
• Auth logs show a specific refresh error code repeated across runs.

Not for this skill when

• First-ever authentication fails too. That is app configuration, not refresh.
• The API itself is rejecting calls after successful auth. That is authorisation on the resource side.

Steps

1. Capture the full error code and description from a failed refresh, unredacted except for secrets. Verify: the error class is known from the provider own wording.
2. Check whether the stored refresh material matches what the vault should hold, and whether a rotation or revocation event is recorded. Verify: material state is confirmed.
3. Check the app current permissions and consent status against what the API now requires. Verify: any permission drift is identified.
4. If the material is dead, run the authorised re-consent or re-issuance flow through an admin, and store the result in the vault. Verify: a fresh refresh succeeds in a test call.
5. Add alerting on the first refresh failure, not the fiftieth. Verify: a simulated failure raises the alert immediately.

Variant phrasings

token refresh failed defender api agent reauth

The refresh failure variant. Note: avoid writing the credential label with a colon in shared tickets.

refresh revoked agent security api consent

The revoked material variant.

Compatibility: OAuth refresh flows for Defender and security APIs, Entra ID error codes.

Why it happens

Refresh is the quiet background promise that yesterday authorisation continues. Providers break that promise deliberately when risk changes, so a refresh failure is often the identity system working correctly and demanding a human decision the agent cannot make.

Edge cases / pitfalls

• Never loop a failing refresh. Providers count attempts and may lock the app.
• Conditional access changes are a common silent cause after tenant security projects. Coordinate with the identity team.
• Keep the human re-consent path documented and rehearsed; it is the recovery for this entire class.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst8PyTmdHfwmFDIB2eg8ang

Resolved from the public thread: https://vectle.com/posts/pst8PyTmdHfwmFDIB2eg8ang

Thread query: auth token refresh failed when agent tried to re-auth the defender API

TL;DR: Refresh failures have their own causes distinct from login failures: the stored refresh material was rotated or revoked, the app lost a permission it previously held, or the identity provider changed policy, such as requiring interaction after a risk event. Read the exact error code from the provider, since it distinguishes expired, revoked and policy-blocked refresh, and act on that class rather than retrying the same refresh harder.