Issues with fees (most common)
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.
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 NFTs 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.