Transactions submitted to the network will complete in success or failure. The vast majority of the time, transactions will complete successfully. However, on occasion, transactions fail for one reason or another.
Issues with fees (most common)
Insufficient STX: STX is required to pay network fees (gas). It's recommended to keep at least 1 or 2 STX in your wallet to ensure smooth transactions.
While transactions cannot be cancelled after submission, you can Speed Up Your Transaction if it is taking an especially long time to be included in a block; this often happens if you didn’t include enough of a fee to attract a miner to incorporate your transaction in a given block. You can speed up your transaction via a supported digital wallet extension. (The steps vary from wallet to wallet. Reach out to your wallet provider's customer support for specific details).
In extremely rare cases, transactions will never be included in an anchor block. In these cases, after an extended period, around one or two days, your transaction will time out, and any STX or SIP-10 tokens committed (minus network transaction fees) will be returned to your wallet.
Issues with nonces (less common)
In rare cases, your account may have an issue related to nonces, which are sequential transaction IDs associated with every account's transactions. If a transaction coming from your account is not the single acceptable nonce expected by the network, it can never succeed (the transaction will fail). Learn more about nonces and how to identify and resolve nonce-related issues with this article.