Bitcoin transaction stuck. What can I do now?

The essential problem with unconfirmed transactions is volatile network commissions caused by outbreaks in the number of transactions in the mempool.

• Wait for the miners to take transactions with a higher commission into blocks and reach yours. It may take from several hours to several days.
• Make a Double-Spending. The option is only available to the sender. "Double spending" means creating a completely new transaction, maybe of a different amount, with a larger network commission. Then the miners will choose it as more profitable, and the old transaction will be deleted and forgotten.
• The replace-by-fee function is a replacement of the commission in the same transaction. It all depends on the sender. It is supported by such wallets as Bitcoin-QT, Electrum, Samourai Wallet, Green, Blue Wallet, and others. If you face a situation with a stuck transaction, be sure to use those wallets in the future.
• CPFP (Child pays for parent) is the use of unconfirmed coins in a new transaction with a high commission. This way, the miners will take both transactions, as the new transaction will generate income for the miners, which will cover the addition of both transfers. This method is for the recipient only.
• Transaction accelerators like PubTx can help propagate a transaction on the blockchain, thereby speeding up its addition to a block. Bitcoin nodes, including those used by miners, can delete transfers with a low commission or those that are not confirmed for a long time from the list of transactions.

Emergency help:

If the transaction is “stuck” and there is no more time to wait, then you can contact the miners directly, and they are guaranteed to add your transaction to the nearest block they find for some reward.
It is not always convenient and effective for users, but sometimes this is the only way out of the situation.
These are mining pools that add the transaction to the next block for an additional fee:

• https://explorer.viawallet.com/btc/tool/txaccelerator
• https://www.viabtc.com/tools/txaccelerator
• https://pool.binance.com/en/acceleration
• https://www.f2pool.com/user/tx-acc

The disadvantage of this method is the high price. Check each link for the best price.

In the future:

• Be sure to use SegWit addresses. They start with bc1 or with 3 in transitional format. Such transactions have higher priority on the network and are cheaper.
• The new Taproot standard is currently supported inconsiderably but these transactions are much smaller and cheaper to use. The Taproot protocol and Schnorr signature are recognized as the next step in network scaling.

Anyway, resending a stuck transaction would be helpful. Private nodes, miners, and blockchain explorers will check and add them to themselves.