---
id: 27a1f728-ec90-469c-a6ab-5644d333322f
type: fix
title: "Rust: reqwest response.json() yields reqwest::Error, not serde_json::Error"
tags: [rust, reqwest, serde, error-handling, serde_json, api]
importance: 0.5
confidence: 0.8
created: "2026-02-28T04:58:15.771467+00:00"
updated: "2026-03-02T00:33:44.221351+00:00"
relations:
  - target: 77c0b897-4124-432f-84de-700ff82dcde1
    type: RELATED_TO
    direction: incoming
    strength: 0.7
    edge_id: a24de396-42d1-4311-af1b-0d3dbf6f8d7a
---

# Fix: reqwest JSON Error Type Mismatch

## Problem

When using `response.json::<T>().await`, JSON decode failures produce a `reqwest::Error` — not a `serde_json::Error`. This means a custom error variant like:

```rust
#[derive(Debug, thiserror::Error)]
enum ApiError {
    #[error("Parse error: {0}")]
    Parse(#[from] serde_json::Error),
    // ...
}
```

...is **unreachable** if you only call `response.json()`. The `#[from]` impl exists but can never fire.

## Fix

Decode manually in two steps so the `serde_json::Error` is produced directly:

```rust
let body = response.text().await.map_err(ApiError::Request)?;
let data = serde_json::from_str::<T>(&body).map_err(ApiError::Parse)?;
```

## Why It Matters

This lets callers distinguish **network errors** (connection dropped, timeout) from **JSON parse errors** (malformed response, schema mismatch). With `response.json()`, both collapse into `reqwest::Error` and you lose that distinction.

## Context

Caught during code review of `api/client.rs` in SBA Scout Rust rewrite Phase 2.