# OpenAI: prompt_cache_options is no longer accepted

> Source: <https://driftwatch.et/changes/openai-2026-11-03-7094f95d>
> Published: 2026-11-03 22:29:31+00:00

## What changed

Usually ignored rather than rejected, so the call succeeds and does something subtly different.

Affects `prompt_cache_options` on `CreateModelResponseProperties` reachable from 2 operations. Grep for it: nothing else will tell you.

## Who is affected

Code that sends OpenAI's CreateModelResponseProperties objects, used by 2 OpenAI operations.

## Before and after

| Where | Before | After | 
|---|---|---|
| CreateModelResponseProperties.prompt_cache_options | present | absent | 
| BetaCreateModelResponseProperties.prompt_cache_options | present | absent | 

## Code that breaks

```
await client.post("/…", {
  // prompt_cache_options is now ignored, not rejected
  prompt_cache_options: value,
});
```

Based on OpenAI’s published API specification. [How severity is decided](https://driftwatch.et/method).