API Error: 400 invalid_parameter_error - Claude Code

Quick fix

Check the base url and model config, enable the rectifier, or ignore the false 400 from Stream Check.

Symptom

Error outputCopy

⎿  API Error: 400 {"error":{"code":"invalid_parameter_error","message":"{\"request_id\":\"9ece554a-3ba4-92b4-b8b0-62d2ef2fb0bd\",\"code\":\"InvalidParameter\",\"message\":\"Request body format invalid\"}","param":null,"type":"invalid_request_error"},"request_id":"08d4cba3-4104-96be-9d53-c07c8351124b"}

Cause

An HTTP 400 usually comes from one of: 1. Using a third-party service such as an Alibaba Cloud coding plan with the wrong base url or model config, or an incompatible request body format (adaptive thinking after 4.6 is not supported, for instance). 2. Input length exceeding the limit (an error such as input length should be [1, 202752]). 3. In cc-switch v3.16.0, Stream Check (connectivity detection) stripping the model name prefix while probing a Chat-format Codex provider and reporting a false positive — though that is separate logic from actual request forwarding.

Fix

1. 1

   Check the base url and model config, making sure you use the address the coding plan provides.

2. 2

   Try enabling the rectifier feature to resolve errors from an incompatible request body format.

3. 3

   If the 400 only appears during connectivity detection (Stream Check) while conversations work, ignore the false positive.

Affected Versions

ToolClaude Code / Codex

Versionv3.16.0 - v3.16.2

PlatformsUnknown

Source Issues

This page is distilled from 3 real issues

• #1139请求增加对阿里云coding plan的支持
• #1210使用阿里云 coding plan 出现异常信息
• #2098Stream check strips provider prefix from model names, causing false 400 errors for third-party Responses API providers

FAQ

Connectivity detection reports 400 — can I still use it normally?

Stream Check and actual proxy forwarding are separate logic, so a detection error does not mean conversations are unusable.

Does the Alibaba Cloud coding plan have no native Anthropic endpoint?

It does, but it does not support adaptive thinking after 4.6, so proxy mode may error.

Related problems

HTTP 401 Unauthorized - CC Switch AnthropicUpgrade cc-switch to a fixed build so it sends the x-api-key and anthropic-version headers Anthropic requires.2 issues mergedAPI Error: 404 - Claude Code path assembly or unregistered routeCheck whether the API address was assembled wrongly, or upgrade cc-switch for the 404 from OpenAI-compatible mode and the missing local route.2 issues mergedmissing field content HTTP 400 - CodexReplace `content:null` with an empty string in CC Switch to fix strict upstream rejections.2 issues merged