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InputValidationError: Write failed - Claude Code

Quick fix

Turn Tool Search, maximum-effort thinking, and the 1M context declaration off in cc-switch to reduce long-text truncation, or roll back to 3.13.0.

Symptom

Section titled “Symptom”
Error output
InputValidationError: Write failed due to the following issues:
  The required parameter `file_path` is missing
  The required parameter `content` is missing

Cause

Section titled “Cause”

When cc-switch routes Claude Code to an OpenAI Chat Completions-compatible endpoint such as Copilot, the parameters of a long-text tool call (Write, Edit) stream back across several SSE frames. In `streaming_codex_chat.rs`, if a chunk's JSON is briefly invalid because of TCP fragmentation, the parse failure triggers a `continue` and the chunk is silently dropped. `json_canonical.rs` then passes the incomplete JSON on as-is, so the client receives an empty object missing required parameters and errors.

Fix

Section titled “Fix”

  1. Roll cc-switch back to 3.13.0, which does not include the streaming parse optimisation causing this and resolves it fully.

  2. To stay on the current version, untick "enable Tool Search", "maximum-effort thinking", and "declare 1M support" in the model mapping in the cc-switch UI.

    环境变量等效配置
    ENABLE_TOOL_SEARCH=0
    CLAUDE_CODE_EFFORT_LEVEL=default

  3. Quit and restart cc-switch and Claude Code completely. If medium-to-long text still fails occasionally, retry the command by hand.

Affected Versions

Section titled “Affected Versions”
ToolClaude Code
Version3.14.1 - 3.16.1
PlatformsWindowsmacOS

Source Issues

Section titled “Source Issues”

This page is distilled from 3 real issues

FAQ

Section titled “FAQ”
Why do tools like Read work while only Write and Edit fail intermittently?
Write and Edit parameters are usually longer, making TCP fragmentation more likely to break SSE frame JSON parsing and get the chunk silently truncated.
Why does retrying the same command sometimes succeed?
A timing dependency: a retry produces new TCP timing and frame boundaries, which may happen to avoid the JSON truncation.
Does setting defaultMode: acceptEdits in settings.json resolve it?
No. The problem is in the cc-switch proxy conversion logic underneath and has nothing to do with Claude Code permission settings.
Section titled “Related problems”
temporarily unavailable, so auto mode cannotUpgrade cc-switch to v3.15.0+ for the model mapping and thinking conversion fixes, or override the default model env var in general config.5 issues mergedsettings.json Full Overwrite Causes Plugin FailureUpgrade to v3.20.1+ to fix the bug that clears enabledPlugins when switching configs.9 issues mergedBody text appears in thinking blocks, visible text nearly emptyUpgrade cc-switch to a build with PR #4210. Reactive thinking-placeholder handling fixes long-context freezes and body-text collapse.1 issues merged

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