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Your input exceeds the context window error - Claude Code

Quick fix

The session context is too long for the model limit. Compact the context by hand or set an auto compact window.

Symptom

Section titled “Symptom”
Error output
API Error: 422 格式转换错误: Your input exceeds the context window of this model. Please adjust your input and   try again.
English translation

API Error: 422 format conversion error: Your input exceeds the context window of this model. Please adjust your input and try again.

Cause

Section titled “Cause”

Using a relay in Claude Code or Codex (connecting gpt5.5 or sonnet 4.6, for instance), a single long session can send a context longer than the real limit of the target model, triggering a 422 format conversion error or a 502. It usually means the context overflowed and could not be forwarded through the routing normally.

Fix

Section titled “Fix”

  1. When the error appears, compact the context of the current session by hand, ahead of time.

  2. Set an auto compact window yourself so the tool compacts automatically once the context reaches a given proportion.

Affected Versions

Section titled “Affected Versions”
ToolClaude Code, Codex
Version3.16.1 - 3.16.2
PlatformsWindowsmacOS

Source Issues

Section titled “Source Issues”

This page is distilled from 2 real issues

FAQ

Section titled “FAQ”
Why does it report exceeding the limit when the context window shows only 54%?
The context window percentage may be calculated against a particular model (the 1M context of sonnet 4.6, for instance), where 54% is 540k — already beyond the context limit of the relay model or routing configuration you actually call.
I keep hitting 502 context-too-long errors on a relay. Is quitting and reopening the only option?
No need to quit and reopen. You can compact the context by hand ahead of time, or configure an auto compact window to keep a long session from interrupting the task.
Section titled “Related problems”
Only a 200K context window shows in actual use - Claude CodeChange the default model in `~/.claude/settings.json` to the `[1m]` variant, or run `/model claude-opus-4-8[1m]` in the session, to activate the 1M context.5 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 mergedClaude Official check failed: could not extract base_url - CodexCC Switch proxying and load balancing do not support an official Claude subscription — use a third-party API key. Forcing it errors and risks a ban.4 issues merged

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