quota_exhausted

The API returns quota_exhausted with HTTP status 402.

A plan limit or monthly allowance is used up (the code varies by endpoint), or the workspace's billing needs attention (billing_locked).

#Where the API reference mentions it

• Placement tests (Accounts)
• Per-lead enrichment and history (Campaigns)
• Quotas are not rate limits (Usage & limits)

#What the response looks like

{
  "error": {
    "code": "quota_exhausted",
    "message": "...",
    "details": null
  }
}

error.code is stable and safe to branch on. error.message is debugging context, not something to parse. The full list of codes, and the rate limits, are on Errors & Rate Limits.