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Upstream HTTP 502 - CC Switch (Claude Code / Codex)

Quick fix

Check your local network proxy (Clash/ZeroTier) config and make sure it does not interfere with direct requests.

Symptom

Section titled “Symptom”
Error output
[FWD-003] Provider s-gpt-20x-local 请求失败: 上游 HTTP 502
English translation

[FWD-003] Provider s-gpt-20x-local request failed: upstream HTTP 502

Cause

Section titled “Cause”

When CC Switch tries to forward a request directly to an upstream service on the LAN (Sub2API, for instance) and the upstream returns HTTP 502, the cause is usually not a defect in CC Switch itself but an intermediate network device or proxy program intercepting the traffic.

In the resolved cases, the problem came from the configuration of a local network management tool (Clash or ZeroTier, for example). Handling particular ports, IPs, or protocols (an SSE streaming response, say), those tools can hit compatibility problems that reset the connection or return a gateway error. Notably, relaying through an extra local Python forwarding proxy can make the request work again, which further points at network-layer interference on the original path rather than an application-layer logic error.

Fix

Section titled “Fix”

  1. Check and adjust the bypass rules or configuration of your local network proxy software (Clash, ZeroTier, V2Ray, and so on) so it does not wrongly intercept or modify traffic to the upstream service IP and port.

  2. Restart the network proxy software or reload its configuration, then retry the request in CC Switch.

Affected Versions

Section titled “Affected Versions”
ToolCodex / Claude Code
Version3.16.1 - 3.16.5
PlatformsWindows

Source Issues

Section titled “Source Issues”

This page is distilled from 2 real issues

FAQ

Section titled “FAQ”
Why does it succeed when forwarded through a local Python proxy?
Because the extra proxy may change HTTP headers (Connection, Accept-Encoding) or buffer the response, sidestepping the way the underlying network proxy software mishandles the original direct traffic.
Is this a CC Switch bug?
In the known cases, no — it is a compatibility problem between the local network environment (Clash/ZeroTier) and the upstream service. CC Switch acts only as a transparent forwarder in this scenario.
Section titled “Related problems”
404 Not FoundDeepSeek does not support the Responses API — use the built-in preset to route through Chat Completions. For image errors, drop the image modality.5 issues mergedHTTP 401 Unauthorized - CC Switch AnthropicUpgrade cc-switch to a fixed build so it sends the x-api-key and anthropic-version headers Anthropic requires.2 issues mergedmissing field content HTTP 400 - CodexReplace `content:null` with an empty string in CC Switch to fix strict upstream rejections.2 issues merged

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