Claude Proxy Errors and Fixes | Generated by AI

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Question: Why does the custom Claude API proxy return a “400 Bad Request” error saying the interface is only for Claude Code clients, and why do subsequent attempts fail with missing credentials or wrong API key?

Answer:

Root Cause Analysis

You’re hitting three separate issues in sequence. Let me break them down:

Issue 1: Proxy Rejects Your Request (400 Bad Request)

默认渠道限制: 请求非法 接口仅可用于Claude Code客户端
(如误判请修改CC客户端版本 其他渠道不限)

Translation: “Default channel restriction: illegal request. This interface can only be used by Claude Code clients.”

Why it happens:

The proxy at https://claude2.sssaicode.com/api is a third-party API reseller/relay. It inspects the HTTP request headers to verify the caller is a legitimate Claude Code client. It checks headers like:

Your custom claw tool doesn’t send the right headers to pass this check.

Fix: The error message itself hints at the solution — “如误判请修改CC客户端版本” meaning “if incorrectly flagged, modify the CC client version.” You need to set your client’s User-Agent or version header to match what official Claude Code sends.

Issue 2: Missing Credentials (after you unset the env var)

error: missing Anthropic credentials; export ANTHROPIC_AUTH_TOKEN or ANTHROPIC_API_KEY

This happened because your second attempt ran after the export ANTHROPIC_API_KEY= command — which set the key to an empty string, and then your shell session may have lost it. The tool correctly complained about missing credentials.

Issue 3: Wrong API Key for OpenAI (401 Unauthorized)

Incorrect API key provided: 999VUv4m**...8MZq

When you switched to --model openai/gpt-4.1-mini, the tool correctly routed to OpenAI’s API — but it used your OPENAI_API_KEY which is invalid or expired on OpenAI’s platform directly. The key 999VUv4m... is likely a key issued by the proxy/reseller, not a real OpenAI key.

Summary Table

Error Cause Fix
400 from proxy claw doesn’t send Claude Code client headers Add correct User-Agent / client version header
Missing credentials ANTHROPIC_API_KEY was set to empty Re-export a valid key
401 from OpenAI OPENAI_API_KEY is a proxy key, not a real OpenAI key Set OPENAI_BASE_URL to the proxy’s OpenAI-compatible endpoint

If the proxy supports an OpenAI-compatible endpoint, try:

export OPENAI_API_KEY=<your-proxy-key>
export OPENAI_BASE_URL="https://claude2.sssaicode.com/api"   # or its openai-compat path
./target/debug/claw prompt "say hello" --model openai/claude-opus-4-6

Or, if you want to use it as an Anthropic endpoint, you need to make claw send headers that mimic the official Claude Code client — specifically the correct User-Agent and possibly an x-claude-code-version header.

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