`TypeError: Converting circular structure to JSON` when downloading Coder binary

[davo-canva]

We're seeing this exception when the extension tries to download a new version of the Coder CLI in Cursor.

TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'TLSSocket'
    |     property 'parser' -> object with constructor 'HTTPParser'

It seems like this only affects older versions of VSCode, as I can't reproduce this in VSCode 1.104.2. The bug was introduced in extension version 1.11.0. The download works when downgrading the extension to version 1.10.1.

The output logs preceding this:

2025-10-02 14:14:18.402 [info] Downloading since existing binary does not match the server version
2025-10-02 14:14:18.403 [info] Removed coder-darwin-arm64.temp-bs1fi
2025-10-02 14:14:18.403 [info] Downloading binary from /bin/coder-darwin-arm64
2025-10-02 14:14:18.437 [info] Using ETag 93ba9ec75313948cc85baadc9914917c70e4350e
2025-10-02 14:14:18.862 [warning] Converting circular structure to JSON
    --> starting at object with constructor 'TLSSocket'
    |     property 'parser' -> object with constructor 'HTTPParser'
    --- property 'socket' closes the circle

The call stack looks like this, when I run in debug mode:

Full stack trace

formatContentLength (/Users/davidv/work/vscode-coder/src/logging/formatters.ts:40)
logResponse (/Users/davidv/work/vscode-coder/src/logging/httpLogger.ts:68)
<anonymous> (/Users/davidv/work/vscode-coder/src/api/coderApi.ts:232)
process.processTicksAndRejections (internal/process/task_queues:95)
Promise.then (Unknown Source:0)
_request (/Users/davidv/work/vscode-coder/node_modules/axios/dist/node/axios.cjs:4599)
request (/Users/davidv/work/vscode-coder/node_modules/axios/dist/node/axios.cjs:4478)
Axios.<computed> (/Users/davidv/work/vscode-coder/node_modules/axios/dist/node/axios.cjs:4647)
wrap (/Users/davidv/work/vscode-coder/node_modules/axios/dist/node/axios.cjs:31)
download (/Users/davidv/work/vscode-coder/src/core/cliManager.ts:253)
fetchBinary (/Users/davidv/work/vscode-coder/src/core/cliManager.ts:133)
await (Unknown Source:0)
processTicksAndRejections (internal/process/task_queues:95)
await (Unknown Source:0)
processTicksAndRejections (internal/process/task_queues:95)
await (Unknown Source:0)
processTicksAndRejections (internal/process/task_queues:95)
await (Unknown Source:0)
setup (/Users/davidv/work/vscode-coder/src/remote/remote.ts:301)
await (Unknown Source:0)

vscode-coder/src/logging/formatters.ts

Line 40 in 67e85e6

const estimated = Buffer.byteLength(JSON.stringify(data), "utf8");

vscode-coder/src/logging/httpLogger.ts

Line 68 in 67e85e6

const len = formatContentLength(response.headers, response.data);

vscode-coder/src/api/coderApi.ts

Line 232 in 67e85e6

logResponse(logger, response, getLogLevel(configProvider()));

vscode-coder/src/core/cliManager.ts

Line 253 in 67e85e6

const resp = await client.get(source, {

vscode-coder/src/core/cliManager.ts

Line 133 in 67e85e6

const status = await this.download(client, binSource, writeStream, {

IDE version information

Cursor Version: 1.7.28 (Universal)
VSCode Version: 1.99.3
Commit: adb0f9e3e4f184bba7f3fa6dbfd72ad0ebb8cfd0
Date: 2025-10-01T02:45:21.769Z
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.6.0

[davo-canva]

It looks like this bug was introduced in #580. Changing the setting introduced in that PR successfully works around the bug.

  "coder.httpClientLogLevel": "none"

2025-10-02 15:59:48.075 [info] Using ETag 93ba9ec75313948cc85baadc9914917c70e4350e
2025-10-02 15:59:48.760 [info] Got status code 200
2025-10-02 15:59:48.760 [warning] Got invalid or missing content length undefined
2025-10-02 15:59:51.730 [info] Downloaded 43.3 MB

[EhabY]

A bit strange that the Axios response.data includes an Node Object like TLSSocket. Can you reproduce this reliably on VS Code 1.99.3 but not the most recent one? Are you trying to connect to the same Coder instance/server?

Thanks for the detailed bug report!

[davo-canva]

Can you reproduce this reliably on VS Code 1.99.3 but not the most recent one?

Yep, I can repro reliably with Cursor (which is stuck on that old VS Code base), and a few of our users can too.

Are you trying to connect to the same Coder instance/server?

This happened to me when I switched the extension to a Coder instance we upgraded since I last connected to it.

[EhabY]

The fix for this has landed and there's already a release on GitHub for it (v1.11.1), let me know if you encounter other issues!