Vapi is the Voice AI platform for developers.

Vapi AI

Was the waitFunction parameter handling just changed?

This was working fine:
```waitFunction: "(x <= 0.5 ? 100 : (x <= 0.8 ? 200 : 300))"```

But all of a sudden it started returning:

```"startSpeakingPlan.smartEndpointingPlan.waitFunction:

The expression 'f(x) = (x <= 0.8 ? 100 : (x <= 0.5 ? 100 : (x <= 0.8 ? 200 : 300))' has invalid syntax.

Math.js error: Invalid left hand side of assignment operator (char 4)"
  ],
  "error": "Bad Request",
  "statusCode": 400
}```

Seems like something was changed on Vapi's side (something to do with f(x) maybe)

What was changed please and can we please get it fixed asap! It was working well

**It appears that the `waitFunction` parameter now only supports direct mathematical expressions and not ternary (`? :`) or assignment (`=`) syntax.** To resolve the error, use a formula like:

```waitFunction: "200 + 8000 * x"```

This will map `x` (probability) to a wait time in milliseconds. For more complex logic, you may need to approximate with a continuous function instead of conditional logic.  
[See documentation for details.](https://docs.vapi.ai/customization/speech-configuration)

Sources:
- [Speech configuration documentation](https://docs.vapi.ai/customization/speech-configuration)
- [Changelog May 7, 2025](https://docs.vapi.ai/changelog/2025/5/7)

Can you send me the CURL request what you are sending?