# concurrency_limited

> Noptcha API error concurrency_limited (HTTP 429): what it means and what to do.

Source: https://noptcha.com/docs/errors/concurrency_limited/

HTTP **429**, `application/problem+json`. When: too many tasks in flight.

## What to do

The organization already has the maximum number of tasks in flight for this captcha family (50 by default). In the sandbox the limit is 20 tasks in flight per organization, across all types. Wait for some tasks to finish, then retry.

See all codes on [Errors](https://noptcha.com/docs/errors.md). Include the `request_id` when you contact support.