# backend_error

> The terminal returned an error for this operation; the MetaTrader code is in `code` or `mt5Code`.

Source: https://tickwire.io/docs/errors/backend_error/

HTTP 500, 502. Unknown: it may have executed. Resolve it with the same idempotency key before acting.

**Likely causes:**

- The terminal refused or failed the call.
- The connection to the terminal failed mid-call.

**What to do:** Reads: retry. Trades: do not resend blindly; repeat only with the same Idempotency-Key, which answers with the real outcome.

**Retry:** Only with the same `Idempotency-Key` (or `clientId`). The first attempt may have executed; never resend a trade blindly.

Listed under [Accounts and terminals](https://tickwire.io/docs/errors/#accounts-and-terminals) in [Errors](https://tickwire.io/docs/errors/). Send the error's `requestId` to support and we can find the request.