If you are encountering this error it means that either:
- Horizon has not received a confirmation from the Core server that the transaction you are trying to submit to the network was included in a ledger in a timely manner or:
- Horizon has not sent a response to a reverse-proxy before in a specified time.
The former case may happen because there was no room for your transaction in the 3 consecutive ledgers. In such case, Core server removes a transaction from a queue. To solve this you can:
- Keep resubmitting the same transaction (with the same sequence number) and wait until it finally is added to a new ledger or:
- Increase the fee.
As with all errors Horizon returns, timeout follows the Problem Details for HTTP APIs draft specification guide and thus has the following attributes: