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Unsupported parameter: 'max_tokens' - Claude Code

Quick fix

The route forwards max_tokens to a model that only accepts max_completion_tokens. Verify parameter support or wait for a cc-switch fix.

Symptom

Section titled “Symptom”
Error output
API Error: 400 Unsupported parameter: 'max_tokens' is not supported with this model. Use 'max_completion_tokens' instead.

Cause

Section titled “Cause”

On Windows, the user switched Claude Code to a GPT model through cc-switch 3.15.0 and enabled routing. The Claude Code request includes `max_tokens`, but the target model or upstream API does not accept that parameter and only accepts `max_completion_tokens`, so it returns 400: `Unsupported parameter: 'max_tokens' is not supported with this model. Use 'max_completion_tokens' instead.` The maintainer asked for a reproducible configuration, but no further details were provided. The fixed version and exact configuration change therefore remain unknown.

Fix

Section titled “Fix”

  1. The issue was closed without a confirmed fix. Reproduce it through the cc-switch route and check whether the selected model supports `max_tokens`. The error says the model requires `max_completion_tokens`, but cc-switch does not replace the field while forwarding. Wait for a cc-switch fix or adjust the upstream configuration manually; issue #3042 does not document a manual procedure.

Affected Versions

Section titled “Affected Versions”
ToolClaude Code
Version3.15.0（受影响版本；修复版本未知）
PlatformsWindows

Source Issues

Section titled “Source Issues”

This page is distilled from 1 real issues

FAQ

Section titled “FAQ”

(No FAQ yet)

Section titled “Related problems”
Symlink target not found: .DirIcon broken symlink causes - CC SwitchAppImage install fails due to broken .DirIcon symlink. Fix by converting it to a relative path.2 issues mergedCC Switch local proxy failed while handlingUpgrade CC Switch to the latest version and start a new Codex conversation; invalid schema or image blocks left in old session history will keep triggering 400.43 issues mergedcc-switch local proxy: 502 Bad Gateway, timeouts, cannot delete a providerUsually caused by unsupported official providers, config not applying, or UI state drift. Check proxy mode, provider type, and takeover state.26 issues merged

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