The Tezos blockchain includes inherent limitations that may affect successful transaction completion:
- One-hour signing timeout
Tezos transaction details always include the last block's hash. In order to be included in a block, transactions are required to reference a block hash within the past 120 blocks. On average a new block is mined every 15 seconds, therefore the transaction must be signed and sent to the blockchain within less than thirty minutes. - One transaction in the mempool at a time
The Tezos blockchain only supports submitting one transaction to the mempool per account at a given time. As a general rule, we support the creation of a new transaction while the previous one is pending in the mempool. However, in this case, the transaction may fail if it reaches the mempool before the previous one is confirmed.