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Oracle Fusion API authentication:
what's changing and what still works

Basic authentication over HTTPS still works for Oracle Fusion REST APIs — but Oracle is steering customers toward OAuth 2.0, newer services require it, and SSO-enabled users can't use basic auth at all. Here's what's actually happening, what the authoritative sources say, and how to connect regardless of your pod's configuration.

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The landscape

Three things Oracle has actually done — not rumoured

Practitioner forums are full of speculation about a forced cut-off. Here's what the published sources say.

Basic auth is discouraged, not disabled

Oracle's October 2025 SaaS Cloud Security blog calls basic authentication "the least secure option" and "strongly discouraged." But disabling it requires a customer-initiated service request through WAF for SaaS — it's opt-in, not platform-mandated. Oracle SaaS Cloud Security blog, Oct 2025

OIC Gen3 already requires OAuth

Oracle Integration Cloud Generation 3 connections to Fusion do not support basic authentication for Factory REST APIs or REST endpoints. Anyone on Oracle's modern integration stack has no choice. Oracle Community, OIC Gen3 discussion

OPC Apps OAuth secrets deprecated (April 2026)

As of 30 April 2026, Oracle-provisioned OAuth client secrets from "OPC Apps" are deprecated. Any integration that copied a client secret from an Oracle-provisioned application must now create its own confidential application under Integrated Applications. OCI Service Change Announcements, March 2026

What still works today

  • Basic authentication over HTTPS to Fusion REST APIs — for non-SSO users, on pods where WAF basic-auth blocking hasn't been enabled
  • OAuth 2.0 with authorization code grant (user-present flow) — the most widely documented path
  • OAuth 2.0 with client credentials grant (server-to-server) — supported but requires service-account setup at the user level, not just the application level
  • SAML 2.0 bearer tokens and JWT assertions — documented alternatives for enterprise identity scenarios

What breaks silently

  • Basic auth when the Fusion user is SSO-federated — credentials don't exist in the local identity store, so REST calls return 401
  • Client credentials grant when the OAuth client is provisioned at the application level rather than the user level — returns invalid_client
  • Any integration still using an OPC Apps client secret copied before April 2026 — Oracle is revoking these
  • Desktop SQL tools (Toad, SQL Developer) — Fusion exposes no SQL*Net or JDBC; these tools cannot connect regardless of auth method
The migration path

OAuth 2.0 client credentials: the setup that trips teams up

The most common server-to-server pattern — and the one with the most undocumented failure modes. Here's what the Oracle Community threads show.

Practitioner reality

The four things that go wrong

  1. 1

    Application-level vs user-level provisioning

    The OAuth client must be provisioned at the user level (Security Console → User → Service Account → OAuth 2.0 client credentials), not just at the application level. Teams that skip this step hit invalid_client with no clear diagnostic. Oracle Community thread, April 2024–present

  2. 2

    IDCS certificate trust

    For OIC Gen2 connections, the Fusion Applications side must trust the IDCS signing certificate — uploaded via Security Console → API Authentication Provider. Gen3 with Fusion SaaS Identity Domain skips this step. OAuth Setup for Fusion ERP Connections, July 2025

  3. 3

    Scope format is pod-specific

    The OAuth scope follows the pattern urn:opc:resource:fusion:{podname}:boss/ — the pod name must match your instance exactly. A typo here produces a valid token that's rejected by the resource server.

  4. 4

    Third-party tools may send the wrong auth header

    Some ISV platforms (SailPoint ISC, for example) include a Basic authorization header by default when requesting an OAuth token — Oracle's IDCS endpoint rejects this format. The fix is to exclude the Basic header on the token request. SailPoint Developer Community, May 2026

QueryWell's approach

Both paths, clearly labelled

QueryWell connects to Fusion through Oracle's supported BI Publisher and REST surfaces. It supports both authentication methods and makes the trade-offs visible.

OAuth 2.0 PKCE — the default

QueryWell defaults to OAuth 2.0 with PKCE (authorization code flow). This is the path Oracle recommends for production use. The app opens your browser for the consent screen, exchanges the code for tokens, and stores them in the OS keychain. No client secret lives on disk.

Basic auth — clearly labelled fallback

When OAuth isn't configured on the pod or the team is still evaluating, QueryWell accepts basic authentication over HTTPS. The UI labels it as a fallback and warns when it's in use. Credentials are stored in the OS keychain, never in plaintext or the app database.

What this means for your integration landscape

If your Fusion pod still accepts basic auth and your integration users are local (not SSO-federated), your existing integrations are not at immediate risk. But every new integration should use OAuth 2.0 — and any integration that copied an OPC Apps client secret needs to be re-registered under its own confidential application. Oracle's direction of travel is clear even without a hard deprecation date: the WAF basic-auth block is available, OIC Gen3 requires OAuth, and the OPC Apps secret deprecation is already in effect.

References

Authoritative sources, not forum speculation

Oracle official

Practitioner & community

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