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:

Description Type Attribute
The identifier for the error. This is a URL that can be visited in the browser URL Type
A short title describing the error String Title
An HTTP status code that maps to the error Number Status
A more detailed description of the error String Detail
A token that uniquely identifies this request. Allows server administrators to correlate a client report with server log files String Instance