A deprecation notice is a promise about a date and a promise about a destination. This one keeps the first promise twice and the second promise differently, depending on which vendor's page you happened to read.
The date
August 26, 2026. Seven days from this record.
OpenAI's deprecations ledger states it plainly:
On August 26th, 2025, we notified developers using the Assistants API of its deprecation and removal from the API one year later, on August 26, 2026.
The page's shutdown table gives the replacement as the Responses API and Conversations API. That is the migration this desk's own deadline board has carried since the row was created.
The other half
Microsoft's Azure documentation for the same feature carries its own notice, and it is not a restatement of OpenAI's:
The Assistants API is deprecated and will be retired on August 26, 2026. Use the generally available Microsoft Foundry Agents service. Follow the migration guide to update your workloads.
Same calendar day. Different destination. An Azure OpenAI customer is not being sent to the Responses and Conversations APIs; they are being sent to Microsoft Foundry Agents, a Microsoft service with its own migration guide.
Neither page mentions the other. OpenAI's ledger is a record of OpenAI's surface and says nothing about Azure. Microsoft's page names its own successor and does not tell the reader that the upstream API is being withdrawn at source on the same date.
Why the pairing matters to somebody
Two concrete failure modes follow, and neither requires anyone to have made a mistake:
A developer running on Azure who reads the upstream notice migrates to the wrong thing. OpenAI's page is the canonical-looking document — it is the API owner's own deprecation ledger — and its named replacement is not available to them as their migration path. The work is real work, and it is aimed at the wrong service.
A developer running on Azure who reads only Microsoft's notice never learns the API is being withdrawn at source. They will migrate, correctly, to Foundry Agents. But the notice they read frames this as a Microsoft product transition, which understates what is actually happening on the 26th.
The single fact that resolves both — this is one upstream withdrawal landing simultaneously on two vendors, with two different exits — is written down in neither place. It only exists when you hold both pages at once, which is precisely the thing no reader is prompted to do.
What changed on this desk
The provider deadline board carried this row with one replacement: Responses and Conversations. That was accurate for OpenAI's surface and incomplete for everyone on Azure. The row now carries both exits and both notices, so a reader arriving from either vendor lands on the pairing rather than on half of it.
This is not a correction to a claim — the row never said anything false. It is a row that was true about one surface and silent about a second one that shares its date.
A note on the date's typography
OpenAI's shutdown table writes the date as 2026‑08‑26 using U+2011, a
non-breaking hyphen, rather than the ASCII hyphen. This desk's term-watch
sweep folds the dash family on both sides precisely so a watched ISO date is
not reported as LOST the first time a page sets it in typographer's
punctuation. It is recorded here because it is the kind of difference that is
invisible to a reader and fatal to a checker, and because anyone building their
own watch on that page will hit it.
Limits of this record
Both quotations are from vendor documentation as it stood on 19 August 2026. Documentation changes; a page that says this today may say something else before the date arrives, which is the entire reason this desk pins the text rather than summarising it.
This record makes no claim about how many deployments are affected, about
whether either replacement is a functional equivalent, or about what will
actually happen to a live call on 26 August. It compares two notices. The
Azure page additionally states it applies to the Foundry (classic) portal,
and carries an updated_at of 24 June 2026.
Source links
- OpenAI deprecations ledger — the August 26 Assistants API shutdown and its Responses/Conversations replacement
- Azure OpenAI Assistants API concepts (classic) — the retirement notice naming Microsoft Foundry Agents
- OpenAI's Assistants migration guide
- Hugin: the provider deadline board, where this row lives
- Hugin: the subscribable deadline calendar
- Hugin: the verification calendar, which watches this page's text
- Hugin: "the check that could not fail" — why the watched terms on this page are record-only strings