How to modify or cancel a pending Ethereum transaction

Ethereum, a blockchain-based open-source software platform that has thousands of decentralized apps (DApps), powers Ether (ETH), its native cryptocurrency. It can be sent and received worldwide without interference from any third-party.

Ethereum was first conceptualized by Vitalik Buterin (Russian-Canadian programmer), in 2013. It is a platform that allows for self-executing, permanent, and immutable DApps. The use cases of Ethereum range from finance to gaming and arts.

DApps, also known as smart contracts, are Ethereum transaction protocols that perform certain functions and actions automatically. These include transaction processing under predetermined conditions and agreements. Smart contracts can be used to send, cancel, or resolve a pending Ethereum transaction.

What is an Ethereum transaction?

Transactions are instructions that have been cryptographically signed from accounts.

Two types of transactions are supported by the Ethereum network: contract deployment transactions, which is a transaction that does not require a receiver, or regular transactions, which is the simplest way to transfer Ethereum from one wallet to the next.

A regular, submitted Ethereum transaction contains the sender’s identifier or signature that is generated when the sender’s private key signs the transaction. This confirms that the sender authorized the specific Ethereum transaction. A submitted regular Ethereum transaction includes the recipient address, the amount of ETH that will be transferred from sender to receiver, information about Ethereum transaction fees, and an optional field for arbitrary data.

To make Ethereum transactions valid, they must be mined and will require payment from the sender.

In order to earn a reward for their efforts in creating new ETH, Ethereum miners must verify that transactions are legitimate. A transaction is validated when a miner solves an cryptographic (mathematical?) puzzle. Ethereum (BTC) has a proof of work (PoW), which prevents cyber attacks by a single person or group.

Users are required to pay a transaction charge when using the Ethereum blockchain. This protects the network from malicious or sloppy computational tasks, such as spamming it with a flood of unrelated transactions.

Lifecycle of Ethereum transactions

An Ethereum transaction is processed through several states. It starts with an unknown state and ends in a block.

Unknown: A transaction that the network hasn’t seen or processed.

Pending: Transactions in the pending status are waiting for miners. This is also known as a “mempool” transaction. Because miners value higher gas prices, transactions with lower gas prices may remain in the pending stage for a longer time. Transactions with low gas prices might not be picked up and remain “stuck in the pending” forever.

In block: A miner who successfully selects and mines a transaction within a block is called an in-block miner. Mined transactions are transactions that occur in-block. A transaction in a block that is forked may return to its pending state. A forked transaction is a transaction that is mined (i.e. one in the in block status) by the network.

Replacing: A transaction can be moved from the current state to the replacement state if one of the following conditions occurs:

A new transaction with the exact same nonce from the sender is entered into the in block state. Or, another transaction with the exact nonce and a 12 percent higher gas price enters into the pending stage. This time, it’s from the sender.

Ethereum Transaction confirmations

The number of blocks that have been created since the initial block that contained this transaction are called Ethereum transaction confirmations.

An Ethereum transaction that is pending must receive confirmations. The more confirmations received, the more certain the Ethereum network will process and recognize the transaction.

Reorganizing blocks from the past can give the illusion that transaction processing was unsuccessful. The transaction can still be valid and included in another block. With each block that is mined after the original, the probability of reorganization decreases. That is, the more confirmations there are, the more immutable the transaction.

Ethereum transaction confirmations

Users pay a transaction fee to encourage block miners. It’s used to send a transaction on the Ethereum blockchain.

Gas fees are the Ethereum blockchain transaction fees. They are related to gas. This pricing mechanism is used on Ethereum network. It refers to the computation required by a miner to process the transaction. Gas cost is used to measure the computational tasks required for a transaction.

Each unit of gas comes with a price in ETH. Gas cost is determined by the complexity of the transaction. However, users have the ability to set their own gas price and gas limit or limit the amount of gas they will consume.

What is a nonce?

Nonce stands for “number only once” and refers to the total number confirmed transactions sent from an Ethereum address.

Ethereum wallets can broadcast multiple transactions to an account without any delay. This means that a nonce calculation will be necessary in order to determine which transaction is processed first. Most often, Ethereum wallet apps take care of nonce administration for users.

How do I cancel an Ethereum transaction

There are two main ways to cancel an pending Ethereum transaction: in application cancellation or setting a custom nuce.

Ethereum transactions can be stuck or pending for hours if submitted with low gas prices. Users often feel the need to modify Ethereum transactions.

Users need to be aware that cancelling a transaction while it is still pending on the network cannot be done. First, they must verify that the transaction is still pending in a block-explorer. To paste the transaction hash (also known as an Ethereum transaction Id), users will need to verify in a block explorer whether the transaction is still pending. Users can cancel it if a block-explorer states “pending”.

In-application cancellation is the best way to cancel an Ethereum transaction that has been stuck. Users must exit the Ethereum wallet app and close it. After closing the browser, reopen the application and log back in.

These steps will not resolve the problem. The second approach will be used.

To cancel an pending Ethereum transaction, set a custom nuce. This will generate a 0ETH transaction with a high price to the user’s address. This is to prevent any previous transactions from being blocked. Users should note the nonce used in the original transaction before sending the second transaction.

Users who have multiple Ethereum transactions pending should prefer to start with the oldest or lowest nonce transaction.

How can you speed up Ethereum transactions?

A user can add gas to an Ethereum transaction to speed it up. This could encourage Ethereum miners prioritize it.

An Ethereum user who sets a lower gas price than the minimum will be able to bid higher and the transaction will still be pending. Once a transaction is confirmed, it will not confirm any more transactions from the same address until the miner confirms that the first transaction was completed.

Users can choose to wait for the network to process the transaction at the specified price or to resubmit the transaction with a higher fee. The transaction should be processed quicker by clicking on the “speed-up” button in the Ethreum wallet.

If the above steps fail, users can go to the advanced tab and manually set the gas price.

Users are encouraged to search for the transaction using the blockchain explorer, posting its hash and checking if it was successful. They can wait for the transaction to appear, or refresh a webpage if it does not.

Is it possible to reverse Ethereum transactions?

Ethereum wallets cannot reverse transactions that have been completed.

Inadvertently sending funds to an incorrect address or the wrong amount of Ethereum can cause the transaction to be cancelled while it is still pending. Once the transaction has been confirmed and marked as “Successful”, it can’t be reversed. Because the Ethereum blockchain is immutable, all data in blocks can be reverted to. It is important to verify that all transaction details are correct before you click the Send button.

It is also worth noting, that many blockchain startups already have mechanisms that allow users to reverse Ethereum transactions.

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