Skip to content
CC Switch WikiUnofficial Community Wiki

Format conversion error: Failed to parse upstream response - Claude Code

Quick fix

Upgrade cc-switch for the streaming response parse fix, or enable full request path and complete the URL for non-standard APIs such as iFlytek.

Symptom

Section titled “Symptom”
Error output
API Error: 422 {"error":{"message":"格式转换错误: Failed to parse upstream response: expected value at line 1 column 1","type":"proxy_error"}}
English translation

API Error: 422 {"error":{"message":"format conversion error: Failed to parse upstream response: expected value at line 1 column 1","type":"proxy_error"}}

Cause

Section titled “Cause”

Several different causes share this 422 format conversion error envelope. The most common: some relay or MaaS gateways still return an SSE streaming response to a request with stream:false while labelling the Content-Type application/json, so cc-switch fails parsing it as JSON. Separately, for APIs using a non-standard path such as iFlytek (/v2 rather than /v1), a wrongly assembled path also returns an unexpected format and triggers the same parse error.

Fix

Section titled “Fix”

  1. Upgrade cc-switch to the latest version. This was fixed structurally on main: on a parse failure the proxy sniffs the response body and, on finding SSE, aggregates it into a normal non-streaming response.

  2. For a non-standard API such as iFlytek MaaS, enable 填充完整请求路径 (fill in the full request path) in cc-switch settings.

  3. Complete the full path in the API address config by hand — append /chat/completions to the URL, for example — or switch to an officially supported Anthropic protocol endpoint such as https://maas-coding-api.cn-huabei-1.xf-yun.com/anthropic.

Affected Versions

Section titled “Affected Versions”
ToolClaude Code
Version3.13.0 - 3.16.1
PlatformsmacOS

Source Issues

Section titled “Source Issues”

This page is distilled from 3 real issues

FAQ

Section titled “FAQ”
Why does the first request work while later ones 422 frequently?
A defect in how the streaming request is judged: the proxy only read the stream value from the first request, so later requests could fail conversion. Upgrade to the latest version for the fix.
Is "Your input exceeds the context window of this model" also a format conversion error?
No — that means your input exceeded the model context window. Compact your input and try again.
Section titled “Related problems”
Error running remote compact taskTurn Remote Compaction off in Codex settings and use local compaction, working around this protocol conversion defect.4 issues mergedError running remote compact task - CodexUpgrade cc-switch to v3.12.0 or newer, which added forwarding for the Codex `/responses/compact` route in the local proxy, fixing the 404 or 502.3 issues mergedinvalid type: sequenceBack up and delete the old config.toml so Codex regenerates a default config, fixing the incompatible hooks format.4 issues merged

This is an unofficial community wiki with no affiliation to the cc-switch authors or the project itself. Its content is compiled from the project's public GitHub issues. This site distributes no software.