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not found(404) adding Claude Code desktop model API - CC Switch

Quick fix

Upgrade to v3.16.3+ to fix connectivity detection false positives, or ignore the 404 and test actual calls directly.

Symptom

Section titled “Symptom”
Error output
not found(404)

Cause

Section titled “Cause”

When adding a custom vendor connection from Claude Desktop to NVIDIA NIM in cc-switch, the interface displays "Interface address does not exist, please check base url and api path" and shows not found(404). This occurs because NVIDIA NIM is an OpenAI-compatible endpoint (path /v1/chat/completions), while Claude Code/Desktop uses Anthropic format (/v1/messages). Although cc-switch proxy handles format conversion, older versions may receive a 404 response during vendor connectivity checks due to protocol mismatches or request differences, marking the check as failed.

Starting from v3.16.3, vendor connectivity checks use lightweight reachability probes instead of sending real streaming requests. Any HTTP response is considered reachable, so it should no longer fail due to 404. Even if the check button still reports 404, switching to the vendor for actual use (via proxy) usually works correctly.

Fix

Section titled “Fix”

  1. Upgrade cc-switch to the latest version (at least v3.16.3 or higher), then retest vendor connectivity.

  2. If the check still fails after upgrading, try ignoring the error and switch to the vendor for actual conversation testing. If actual calls work normally, this indicates only the detection logic was flawed and usage is unaffected.

Affected Versions

Section titled “Affected Versions”
ToolClaude Code
Version>= 3.14.0, < 3.16.3
PlatformsWindows

Source Issues

Section titled “Source Issues”

This page is distilled from 2 real issues

FAQ

Section titled “FAQ”
Why can I successfully call via terminal but not via desktop?
Terminal (CLI) and Desktop may use different configurations or connection methods. Additionally, older versions' connectivity detection logic is more sensitive to non-standard requests. After upgrading to the new version, the detection logic is optimized and typically identifies connectivity correctly.
NVIDIA NIM is an OpenAI-compatible endpoint, why can Claude use it?
The cc-switch proxy layer converts Anthropic-format requests to OpenAI-compatible format before sending them to NVIDIA NIM, and converts responses back to Anthropic format for Claude. Therefore, as long as the proxy works properly, interoperability is achieved even if underlying API formats differ.
What if it still reports 404 after upgrading?
If connectivity checks still report 404 after upgrading but actual conversations or file operations work normally, you can ignore the error. This is a known limitation of the detection logic and does not affect actual functionality. If actual calls also fail, provide the base_url, full error message, and the button that triggered the error (connectivity check or model test) for further troubleshooting.
Section titled “Related problems”
Bash(...) Waiting... Claude CodeDowngrade Claude Code to v2.1.104 or v2.0.64 (admin required), or switch to a compatible provider such as Alibaba Cloud Bailian.1 issues mergedKMS: DRM_IOCTL_MODE_CREATE_DUMB failed: Permission deniedResolve cc-switch white screen DRM permission errors on Linux by disabling WebKit hardware acceleration, specifying NVIDIA rendering, or using the CLI version.2 issues mergedClaude Code Tool Call Failure via NVIDIA Proxy - CC Switch FixNVIDIA free-tier models are unstable; switch to stable providers like deepseek-ai/deepseek-v4-flash.2 issues merged

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