---
title: V4.2
description: Upgrade guide from older versions to FastGPT V4.2
---

99.9% of users are unaffected. The V4.2 upgrade primarily changes the `QAModel` format in the configuration file, converting it from an array to an object:

```json
"QAModel": {
    "model": "gpt-3.5-turbo-16k",
    "name": "GPT35-16k",
    "maxToken": 16000,
    "price": 0
}
```

The rationale behind this change is that there's no need to offer multiple choices — just pick the most suitable model for the task.