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unexpected end of data: Codex stream interruption with Xiaomi MiMo

Quick fix

No verified fix is provided in the original post. Codex receives HTTP 400 and the conversation is interrupted after a MiMo tool call.

Symptom

Section titled “Symptom”
Error output
{"error":{"message":"CC Switch local proxy failed while handling Codex endpoint /responses. Provider: Xiaomi MiMo; model: mimo-v2.5-pro; upstream_status: HTTP 400; cause: data:{\"error\":{\"code\":\"400\",\"message\":\"unexpected end of data: line 1 column 120 (char 119)\",\"param\":\"\",\"type\":\"BadRequest\"}}","type":"upstream_error","code":"cc_switch_upstream_error","param":null,"provider":"Xiaomi MiMo","model":"mimo-v2.5-pro","endpoint":"/responses","upstream_status":400}}

Cause

Section titled “Cause”

Reports show that when Codex calls Xiaomi MiMo's `/responses` endpoint through the CC Switch local proxy, the upstream returns HTTP 400, then output stops and the conversation cannot continue. Multiple users reported that this often occurs in multi-turn conversations, tool calls, or after executing the next step; some also said ClaudeDesktop and Codex both stop streaming in these scenarios.

Some participants speculated that `reasoning_content` may be involved during Response API and chat completions structure conversion, tool-call context transfer, or return processing, but this is only user speculation. The original post does not confirm a root cause or merged fix. Someone suggested using `mimo-v2.5` instead of `mimo-v2.5-pro`, but another user reported that `mimo v2.5` also stops streaming, so this cannot be considered a verified fix.

Fix

Section titled “Fix”

  1. No verified fix is provided in the original post. To try the community suggestion, switch to `mimo-v2.5` for comparison testing; however, users have reported that this model also stops streaming, so it is not guaranteed to work.

  2. Follow the discussion in Issue #3561, and retain the upstream HTTP 400 and tool-call context when streaming stops, to help determine whether `reasoning_content` return processing is involved.

Affected Versions

Section titled “Affected Versions”
ToolCodex
Version受影响：3.16.1
PlatformsmacOS

Source Issues

Section titled “Source Issues”

This page is distilled from 1 real issues

FAQ

Section titled “FAQ”
Is there a fix for this stream interruption?
No verified fix is provided in the original post. Someone suggested replacing `mimo-v2.5-pro` with `mimo-v2.5`, but users also reported that `mimo v2.5` stops streaming.
Why does Claude not have stream interruptions while Codex does?
The original post reports this behavior, and someone speculated that it may involve Codex's Response API, tool-call context, and `reasoning_content` return processing; this speculation has not been confirmed.
Section titled “Related problems”
401 UnauthorizedUpgrade to cc-switch 4.0.x, or clear the stale third-party OPENAI_API_KEY from ~/.codex/auth.json manually, restart Codex, and sign in again with ChatGPT OAuth.2 issues mergedapi failed deserialize json body intoDepending on the error: roll Claude Code back, upgrade cc-switch, turn the local proxy off, or stop sending unsupported fields.8 issues mergedRequest exceeds the context windowNo verified solution was provided in the original post; this issue was closed as a duplicate related to catalog configuration and automatic compression.1 issues merged

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