4 legacy completion models reach shutdown

Verification is under 30 days old, not a live check; date passage does not confirm shutdown.

What changed

Impact summary

OpenAI lists Sep 28, 2026 as the shutdown date for 4 legacy model identifiers.

BeforeLegacy completion and older chat snapshots

After / replacementgpt-5.6-terra

Affected models and systems

gpt-3.5-turbo-instructbabbage-002davinci-002gpt-3.5-turbo-1106

Migration action

Recommended next step: Search code, stored prompts and fine-tuning references for all listed model IDs. Move production traffic to gpt-5.6-terra and run response-quality regression tests.

Source and interpretation

API platform & regional scope

OpenAI direct API · Direct developer platform; eligibility and regional restrictions are account-specific.

Not Azure OpenAI.

Bounded manual catalog. Original event checks retained from 2026-09-01; not reverified in this expansion.

Unconfirmed regions are not assumed to be global. Automatic monitoring is OFF. Source checks

Official evidence locators

Existing normalized record: evt_openai_legacy_completion_sep_2026. Locate listed affected model(s) in the lifecycle/release table; original manual check retained.

Original source date and qualifier retained; exact shutdown time is not inferred.

Affected endpoints: Not separately specified; check model / capability scope

Action / deadline: Review required · Stated deadline

This record is classified as official announcement. The facts above were normalized from the provider's public developer documentation. API Change Watch does not treat an unreviewed page diff as a verified announcement.

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