What causes "${label} returned a non-JSON response" in jackwener/OpenCLI?

Check the base URL — it must be the Atlassian site root (e.g. https://example.atlassian.net) or a reachable REST base, not a login/portal page.

jackwener/OpenCLI · error · CommandExecutionError

${label} returned a non-JSON response

Error message

${label} returned a non-JSON response

What it means

atlassianRequest throws this when the HTTP response was OK (2xx) but the body could not be parsed as JSON — the parsed result is a string. The Atlassian REST API is expected to return JSON, so a string body almost always means something other than the API answered (HTML login/SSO page, proxy intercept, or a wrong URL that serves HTML with 200).

Source

Thrown at clis/_atlassian/shared.js:218

        );
    }
    if (resp.status === 404) {
        throw new EmptyResultError(label, `Atlassian returned 404 for ${url}.`);
    }
    if (resp.status === 409) {
        throw new CommandExecutionError(
            `${label} returned HTTP 409: ${summarizeApiError(parsed, 'version conflict')}`,
            'Reload the current Confluence page version and retry the update.',
        );
    }
    if (resp.status === 429) {
        throw new CommandExecutionError(`${label} returned HTTP 429 (rate limited)`, 'Wait and retry with a smaller limit.');
    }
    if (!resp.ok) {
        throw new CommandExecutionError(`${label} returned HTTP ${resp.status}: ${summarizeApiError(parsed, resp.statusText)}`);
    }
    if (typeof parsed === 'string') {
        throw new CommandExecutionError(
            `${label} returned a non-JSON response`,
            'Expected Atlassian REST API JSON. Check the base URL and whether an HTML login, SSO, or proxy page was returned.',
        );
    }
    return parsed;
}

export function queryString(params) {
    const qs = new URLSearchParams();
    for (const [key, value] of Object.entries(params)) {
        if (value === undefined || value === null || value === '') continue;
        if (Array.isArray(value)) {
            for (const item of value) qs.append(key, String(item));
        } else {
            qs.set(key, String(value));
        }
    }
    const s = qs.toString();

View on GitHub (pinned to 49907e53dc)

Solutions

Check the base URL — it must be the Atlassian site root (e.g. https://example.atlassian.net) or a reachable REST base, not a login/portal page.
Re-run with curl to see the actual HTML body and identify who produced it (SSO provider, proxy, captive portal).
Whitelist the tool in the corporate proxy or run from a network without the intercepting proxy.
For Data Center, ensure the deployment setting matches the instance so the correct REST path prefix is used.
If an SSO redirect is unavoidable, use a personal access token / API token so requests authenticate before the SSO page is served.

Example fix

// before (base URL points at a portal that serves HTML 200)
ATLASSIAN_BASE_URL=https://intranet.corp.com/confluence-home
// after
ATLASSIAN_BASE_URL=https://example.atlassian.net

Defensive patterns

Strategy: try-catch

Validate before calling

// preflight: verify the endpoint returns JSON before real work
const res = await fetch(`${baseUrl}/rest/api/space?limit=1`, { headers: authHeaders() });
const ct = res.headers.get('content-type') || '';
if (!ct.includes('application/json')) throw new Error('Endpoint did not return JSON — check base URL/proxy');

Type guard

function isJsonObject(v) { return v !== null && typeof v === 'object' && !Array.isArray(v); }

Try / catch

try {
  const data = await cmd(args);
} catch (e) {
  if (/non-JSON response/.test(e.message)) {
    console.error('Got HTML instead of JSON — SSO/proxy intercept or wrong base URL. Inspect with curl.');
  } else throw e;
}

Prevention

Always use the site root URL (https://example.atlassian.net), not portal/login pages.
Test connectivity from the same network the tool runs on (proxies/VPNs differ).
Use token auth so requests never land on an SSO HTML page.
Check content-type: application/json in a preflight request.

When it happens

Trigger: The base URL points at a server that returns HTML with status 200 — e.g. an SSO/login redirect, a captive proxy, an expired session page, or a typo'd base URL hitting a website instead of the REST endpoint.

Common situations: Corporate proxy injecting an authentication page; ATLASSIAN_BASE_URL missing the /wiki or /rest path context so a portal page is served; VPN/captive portal returning an HTML block page; pointing cloud credentials at a self-hosted instance whose login screen returns 200 HTML.

Related errors

AI-assisted analysis of jackwener/OpenCLI@49907e53dc (2026-08-29). Data as JSON: /api/errors/223a17702fc2286c. Report an issue: GitHub.