On October 23, 2026, the OpenAI model shutdown retired a generation of models — gpt-4-0613, gpt-4-turbo, o1, o3-mini, o4-mini, gpt-image-1 — per their published shutdown schedule. This cybersecurity news memorial keeps the dates, the migration lessons, and the eulogies in one place. The line is open. Leave your eulogy.
Seeded examples are labeled as such. Anything you leave appears with a “yours” tag and stays on this device.
Treat every pinned model as temporary: audit where model names appear in your code, test the vendor's recommended replacement against your own evals, and measure behavior, latency, and cost before switching traffic. Teams that planned the migration as a scheduled task moved calmly; teams that pinned o1 in production with no fallback scrambled mid-incident when the API calls started failing.
⚰️ THE MODEL AUTOPSY · EDITION 01 — FOLDED INTO THIS PAGEA model shutdown is the date a vendor retires an AI model: after it, API calls to that model fail. Shutdowns arrive on a published deprecation schedule, and they routinely change behavior, latency, and pricing on the replacement — which is why migration is a scheduled task, not an emergency.
The Model Autopsy column used to live on its own page. o1's cause of death taught too much to leave behind — so the full post-mortem moved here, on the OpenAI model shutdown memorial page.
o1 (September 2024 – October 2026) was OpenAI's first reasoning model: instead of answering immediately, it worked through problems step by step with an internal chain-of-thought before responding. That made it the go-to pick for complex reasoning work — math, science, and code reasoning tasks where thinking longer beats answering faster. The tradeoff was real too: reasoning models are slower and more expensive per task than chat models, and the hidden chain-of-thought meant less visibility into why it answered the way it did.
Sourcing: retirement date and batch from OpenAI's published deprecation schedule; model characteristics from public documentation. No invented benchmarks on this page — if we didn't see it published, we don't claim it.
Per OpenAI's own migration guidance, OpenAI's stated successor path is the GPT-5.x reasoning model line. That's the vendor's recommendation, not ours — and "recommended" doesn't mean "identical." Every migration we've watched has three surprise dimensions: answers behave differently on edge cases, latency profiles change, and the price per 1,000 tasks moves. Budget for all three.
Honestly: teams that pinned o1 in production and never built a migration plan. Hardcoded model names in API calls, o1 assumed in prompts and system messages, pricing built on o1's token costs, and products whose demo was o1's reasoning style. If that was you, the shutdown didn't create the problem — it revealed it. The fix isn't a faster migration, it's never pinning a single vendor model in production again.
Want the fuller obituary? Read the o1 shutdown obituary and browse the model obituaries archive.
The vendor sets a shutdown date; after it, API calls to the model fail and must be moved to a replacement. Deprecations can also raise prices and change behavior â price the migration before the deadline, don't scramble after it.
OpenAI's October 23, 2026 shutdown wave covers gpt-4-0613, gpt-4-turbo, o1, o3-mini, o4-mini, gpt-image-1 and ft-* models, per OpenAI's published deprecation schedule. GPT-5.6 Sol is the vendor-named replacement.
It depends on your token volume and which replacement you pick. Run the numbers in our migration cost calculator â it compares the vendor-recommended path against a cheaper alternative so you can price the move before the deadline.
October 23, 2026, in OpenAI's published shutdown batch alongside gpt-4-0613, gpt-4-turbo, o3-mini, o4-mini, gpt-image-1 and fine-tuned ft-* models. After the cutoff, API calls to o1 fail and must be moved to a replacement.
OpenAI's stated successor path is the GPT-5.x reasoning model line, per OpenAI's own migration guidance. Test the replacement on your own evals before cutting over â behavior, latency and cost will differ from o1.
o1 (Sep 2024 â Oct 2026) was OpenAI's first reasoning model. It worked through problems step by step with an internal chain-of-thought before answering, which made it strong on complex reasoning tasks like math, science and code reasoning â at the cost of slower responses than chat models.
Audit every place the model is pinned, run the vendor's recommended replacement against your own evals, and compare behavior, latency and cost before switching traffic. Watch pinned model names in config files â they are the most common migration trap.
Your API calls return errors and the feature breaks for users. Teams that pinned o1 in production without a fallback had to scramble mid-incident or ship degraded answers â migration is a scheduled task, not an emergency response.
ModelMinder watches the deprecation schedules for every major AI vendor and pings you before a sunset hits your code. Early access is open.
Get ModelMinder early accessEulogies are community messages, not official statements. · Oct 2026