FetchResponseError: HTTP 200 response does not appear to originate from GitHub.

[yermulnik]

Today I had got npx upgraded as part of node package via Homebrew so that npx version now is 11.12.1.
And copilot.vim started to throw the below error log on initialization:

init log

[2026-05-08 21:43:29] <-! npm warn exec The following package was not found and will be installed: @github/copilot-language-server@1.483.0
[2026-05-08 21:43:31] [INFO] [ripgrep] Set GITHUB_COPILOT_RIPGREP_PATH_OVERRIDE=/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/bin/linux/x64/rg
[2026-05-08 21:43:31] [INFO] [lsp] GitHub Copilot Language Server 1.483.0 initialized
[2026-05-08 21:43:31] [INFO] [UndiciFetcher] HTTP settings changed; resetting Undici dispatchers. {
  proxy: 'none',
  noProxyCount: 0,
  proxyStrictSSL: true,
  hasProxyAuthorization: false,
  hasProxyKerberosServicePrincipal: false
}
[2026-05-08 21:43:31] [WARN] [default] Policy watcher not available - continuing without policy watching: Unsupported platform
[2026-05-08 21:43:31] [INFO] [certificates] Removed 2 expired certificates
[2026-05-08 21:43:31] [INFO] [UndiciFetcher] Root certificate set changed; resetting Undici dispatchers. { certificateCount: 289 }
[2026-05-08 21:43:31] [INFO] [certificates] Removed 2 expired certificates
[2026-05-08 21:43:31] [INFO] [certificates] Removed 2 expired certificates
[2026-05-08 21:43:31] [ERROR] [GithubAvailableEmbeddingTypes] Error fetching available embedding types ProxiedResponseError [FetchResponseError]: HTTP 200 response does not appear to originate from GitHub. Is a proxy or firewall intercepting this request? https://gh.io/copilot-firewall
    at apiFetch (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:1523:8592)
    at processTicksAndRejections (node:internal/process/task_queues:104:5)
    at GithubAvailableEmbeddingTypesManager.doGetAvailableTypes (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2582:21243)
    at GithubAvailableEmbeddingTypesManager.getAllAvailableTypes (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2582:20923)
    at GithubAvailableEmbeddingTypesManager.getPreferredType (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2582:21752)
    at WorkspaceChunkSearchService.tryInit (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2615:38351) {
  code: 'HTTP200'
}
[2026-05-08 21:43:32] [ERROR] [GithubAvailableEmbeddingTypes] Error fetching available embedding types ProxiedResponseError [FetchResponseError]: HTTP 200 response does not appear to originate from GitHub. Is a proxy or firewall intercepting this request? https://gh.io/copilot-firewall
    at apiFetch (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:1523:8592)
    at processTicksAndRejections (node:internal/process/task_queues:104:5)
    at GithubAvailableEmbeddingTypesManager.doGetAvailableTypes (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2582:21243)
    at /home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2582:21101
    at GithubAvailableEmbeddingTypesManager.getPreferredType (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2582:21752)
    at WorkspaceChunkSearchService.tryInit (/home/georgii/.npm/_npx/e9e522e871635100/node_modules/@github/copilot-language-server/dist/main.js:2615:38351) {
  code: 'HTTP200'
}
[2026-05-08 21:43:32] [INFO] [GithubAvailableEmbeddingTypes] Could not find any available embedding types. Error: requestFailed

I've checked this on another server with npx version 11.3.0 and copilot.vim inits with no issues.
Installing 11.12.1 version of npx there results in copilot.vim throwing the same errors.

Is this something copilot.vim (or copilot-language-server) can resolve or this is something npx/node side of things?

[yermulnik]

Hmm, the latest node version that is distributed via Homebrew at the moment is 26.0.0. The npx is distributed as part of node package. npx reports its version as 11.12.1.
If I downgrade to the previous node version distributed via Homebrew, which is 25.9.0_3, the reported version of npx remains the same (11.12.1), but the ProxiedResponseError in copilot.vim init log disappears and there are no issues with plugin initialization.
So the issue seems to be not npx but node (or some other component) — I'm not really familiar with NodeJS 😥️

[yermulnik]

Just in case: I'm testing this from two independent machines from different networks where no mitm/proxy exist.

The let g:copilot_proxy_strict_ssl = v:false and NODE_TLS_REJECT_UNAUTHORIZED=0 don't help.

> curl -i https://copilot-proxy.githubusercontent.com/_ping
HTTP/2 200
content-security-policy: default-src 'none'; sandbox
content-type: application/json
strict-transport-security: max-age=31536000
content-length: 48
date: Fri, 08 May 2026 21:23:08 GMT
x-github-backend: Kubernetes
x-github-request-id: CCD6:33FDDA:96751:DD2BC:69FE543C

{"now":1778275388,"status":"ok","ns1":"200 OK"}