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Deepseek V4 API Error: 400 The reasoning_content in the thinking mode must be passed back to the API #3695

@terrylo11399-art

Description

@terrylo11399-art

What happened?

Still encounter the reasoning_content issue after applying the nightly patch released on Apr 28, 2026

What did you expect to happen?

solve the ✕ [API Error: 400 The reasoning_content in the thinking mode must be passed back to the API.]

Client information

Qwen Code: 0.15.3 (dad9832)
Runtime: Node.js v24.14.0 / npm 11.9.0
OS: win32 x64 (10.0.26200)
Auth: API Key - openai
Base URL: https://api.deepseek.com/v1
Model: deepseek-v4-flash
Fast Model: deepseek-v4-flash
Session ID: fec26666-7e38-448d-81ae-551c245473d5
Sandbox: no sandbox
Proxy: no proxy
Memory Usage: 233.9 MB

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    duplicateIssue duplicates an existing report.type/bugSomething isn't working as expected

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