Yesterday I got this email: [Screen Shot 2023-09-29 at 6.52.23 PM] Why the extremely sudden deprecation? Will there be an endpoint which returns log-probabilities of an inputted completion given an inputted prompt? Maybe also see this tweet by the guy who created GitHub Copilot

Probably because it is too useful… Same reason they thought they would take away the edit button of ChatGPT conversations? It lets you explore training and quality. For example, something I just ran: The most preeminent and notable scientist of the 20th century is I can traverse the tokens and…

Another reason to hide for shame: One can track model perplexity. With logprobs, we can daily dump text and see exactly when the model has become more uncertain.

Why will gpt-3.5-turbo-instruct no longer support echo=true and logprobs=1?

API Feedback

Topic		Replies	Views
You Are Not Allowed To Request Logprobs From This Model: gpt-5-chat-latest API gpt-5	1	737	August 10, 2025
GPT-4.5-preview model will be removed from the API on 2025-07-14 Deprecations	23	13207	August 13, 2025
Logprobs deprecated for gpt-5 models? Deprecations	1	3067	September 2, 2025
Get logprobs for prompt tokens, not just for completion? API logprobs	3	2314	January 20, 2026
O4-mini-deep-research & o3-deep-research deprecation Deprecations	1	109	April 23, 2026

Why will gpt-3.5-turbo-instruct no longer support echo=true and logprobs=1?

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