Stuck Transaction

The most common reason a transaction gets stuck is insufficient gas. This includes:

• Gas Price Too Low: The offered price per unit of gas is below the current network demand, causing miners/validators to prioritize higher-paying transactions.
• Gas Limit Too Low: The transaction's computational complexity exceeds the allocated gas limit, causing it to run out of gas and fail before completion.

Pending transactions reside in a shared network queue called the mempool. A transaction becomes stuck when:

• It's outbid by newer transactions with higher fees.
• The mempool is congested during periods of high network activity.
• It has a nonce issue, where a previous transaction from the same address is also pending.

Each account has a sequential nonce that must increment with each transaction. A stuck transaction can block all subsequent ones if:

• A transaction with a lower nonce is still pending.
• A user accidentally reuses a nonce, creating a conflict.
• A transaction is replaced or canceled, but the original is still propagating.

Users can often "unstuck" a transaction by submitting a new one with the same nonce but a higher gas price. This is known as:

• Gas Bumping or Fee Replacement: Replacing the pending transaction to incentivize inclusion.
• Cancel Transaction: Sending a new transaction with the same nonce, a zero ETH value, and a higher gas price to the sender's own address.

How transactions get stuck and can be resolved varies by chain:

• Ethereum: Users can use the replace-by-fee (RBF) technique if the original transaction allowed it, or cancel via a same-nonce transaction.
• Bitcoin: Relies on Replace-By-Fee (RBF) or Child-Pays-For-Parent (CPFP) transactions to increase priority.
• EVM Chains (Polygon, BSC): Similar to Ethereum, but often with lower base fees and different congestion patterns.

To avoid stuck transactions:

• Use a gas estimator or wallet that suggests appropriate fees based on real-time network conditions.
• Monitor mempool activity (e.g., on Etherscan) before sending large or time-sensitive transactions.
• Understand EIP-1559 (on Ethereum): Set both a maxPriorityFee and maxFee to handle base fee fluctuations.
• Ensure transaction nonces are managed correctly, especially when using advanced wallets or scripts.

The most common cause. A transaction's gas price (fee per unit of computational work) is set too low to outbid other pending transactions. Miners/validators prioritize higher-fee transactions. The transaction remains in the mempool indefinitely until the fee becomes competitive or it is replaced.

• Example: Sending a transaction with a 10 Gwei gas price when the current network base fee is 30 Gwei.

Every account has a nonce—a sequential transaction counter. If a transaction with a nonce higher than the expected next value is sent, it cannot be processed until all preceding nonces are executed. This creates a nonce gap.

• Common in: Automated systems or wallets that send multiple transactions in rapid succession, where one may fail or be delayed.

During periods of high demand, the network's block space becomes a scarce resource. Even transactions with reasonable fees can be delayed as the mempool backlog grows. Transactions may be outbid by a flood of higher-paying ones, effectively becoming stuck in the queue.

• Indicators: Skyrocketing base fee (EIP-1559) or median gas price.

The gas limit is the maximum computational work a transaction can consume. If a transaction's execution (e.g., a complex smart contract interaction) requires more gas than its limit, it will run out of gas and fail. The transaction is included in a block but reverted, and the sender loses the gas paid.

• Different from low gas price: This is a hard execution failure, not a prioritization issue.

The transaction may be stuck locally due to problems with the user's connection to a blockchain RPC node. The node may not be properly broadcasting the transaction to the network, or may be out of sync, giving the false impression of a stuck transaction.

• Solution: Resubmit the transaction through a different, reliable node provider.

Stuck transactions are typically caused by insufficient gas fees or nonce mismatches. When a user submits a transaction with a gas price lower than the current network demand, validators prioritize higher-paying transactions, causing indefinite stalling. A nonce mismatch occurs when a transaction with a specific nonce is pending, blocking all subsequent transactions with higher nonces from being processed.

For users, a stuck transaction creates capital lockup, where funds are temporarily unusable. It can also cause state inconsistency in dApps expecting the transaction to succeed. In extreme cases, it can block an entire wallet's activity if it creates a nonce gap, preventing any further transactions from that address until the issue is resolved.

At the network level, a high volume of stale, low-fee transactions can bloat the mempool, increasing latency for all users. While not a direct security threat, it degrades user experience and can create temporary inefficiencies in transaction ordering and block space utilization.

The most common user-initiated fix is Replace-by-Fee (RBF), where a new transaction is broadcast with the same nonce but a significantly higher gas price. This signals miners to replace the old transaction. Not all networks or wallets support RBF natively. On Ethereum, users can also use the "Cancel" method, sending a zero-ETH transaction to themselves with the same nonce and a higher gas fee.

For transactions stuck due to nonce issues, manual nonce management is required. Users can reset their wallet nonce by broadcasting a new transaction with the correct next nonce, often requiring direct interaction with a node RPC. Some wallets offer "speed up" or "cancel" features that automate this process by managing the nonce and gas price internally.

Prevention relies on accurate gas estimation. Wallets should use dynamic fee estimators that pull real-time data from oracles or nodes. Users should avoid setting maximum priority fees too low during periods of high congestion. Network upgrades like EIP-1559 (Ethereum) introduce a base fee mechanism, making fee estimation more predictable and reducing the frequency of stuck transactions.

A nonce is a sequential number assigned to each transaction from a specific wallet, ensuring order and preventing replay attacks. A transaction with a nonce that is too high (e.g., you try to send nonce 5 before nonce 4 is confirmed) will be queued and appear stuck until the preceding transactions are processed.

On networks like Ethereum, a transaction can be outbid and stuck in the mempool if its gas price (pre-EIP-1559) or priority fee (max priority fee per gas, post-EIP-1559) is too low relative to current network demand. Miners/validators prioritize transactions offering higher fees, leaving low-fee transactions pending indefinitely.

The mempool (memory pool) is a network node's holding area for unconfirmed transactions. A transaction is "stuck" here if it fails to be included in a block. Congestion, low fees, or invalid states can cause a transaction to linger in the mempool until it is eventually picked up or drops out after a timeout period.

A common method to unstuck a transaction is to replace it by sending a new transaction with:

• The same nonce.
• A significantly higher gas fee (priority fee).
• A higher max fee per gas (on EIP-1559 networks). This new transaction overrides the old one, allowing users to effectively cancel or accelerate the original pending transaction.

A transaction may appear stuck due to problems with your connection to a blockchain RPC node. If the node is out of sync, has a poor connection, or is using a pruned archive, it may not broadcast your transaction properly or show accurate confirmation status. Switching to a reliable, healthy RPC endpoint can resolve this.

A chain reorg occurs when a previously confirmed block is orphaned in favor of a longer, competing chain. Transactions in the orphaned block return to the pending state. While temporary, this can make a transaction appear stuck or even "reversed" until it is included in the new canonical chain.