Why is my Ethereum transaction underpriced during network congestion
When Ethereum network traffic spikes, transaction fees follow. Your wallet sets a maximum fee per gas and a priority fee (tip) for the validator. During congestion, the base fee - the portion of the fee that burns - rises automatically. Validators also select transactions offering higher priority fees. If either of your limits falls below what the current market demands, the network rejects your transaction as "underpriced."
The term "underpriced" does not mean your transaction is broken. It means the fee you offered is too low for the moment you broadcast it. Gas prices on Ethereum can shift dramatically within seconds; a fee that worked five minutes ago may be insufficient now.
What causes the underpriced error
Ethereum blocks have a target size of 15 million gas. When demand exceeds that, the protocol raises the base fee per gas. This increase can cascade across successive blocks. Your transaction may have been crafted when the base fee was lower, but by the time it reaches a validation node, the base fee may have climbed past your maximum.
Validators also rank pending transactions by the priority fee attached. If you set a low priority fee, your transaction sits at the back of the mempool queue. During heavy congestion, only transactions with competitive priority fees get included; the rest remain pending or return the underpriced error.
How to fix an underpriced transaction
First, check current network conditions. Etherscan offers a gas tracker on its homepage, and gas oracle sites like GasNow or ETH Gas Station also show live data. Look at the current base fee and the average priority fee for fast inclusion.
Once you have the numbers, create a new transaction with the same nonce as the failing one. The nonce is a sequential number that orders your transactions. Using the same nonce cancels the old transaction and replaces it. Set your max fee per gas above the current base fee plus your intended priority fee, and set the max priority fee to at least the average shown by the gas oracle.
For example, if the gas tracker shows a base fee of 50 gwei and average priority fee of 5 gwei, set your max fee to at least 60 gwei and max priority fee to 6 gwei. This gives you a small buffer above the current market. Most wallets like MetaMask or Rabby allow manual fee adjustment. Enable advanced gas controls to enter custom values.
Replacement underpriced error
The "replacement underpriced" error is different. It occurs when you try to replace an already-pending transaction with one that does not offer enough additional fee. Ethereum requires a 10% minimum fee bump for replacements, so if you attempt to resubmit with a fee that is too close to the original, the network rejects it.
Calculate a proper replacement: take your original max fee and multiply by 1.1. Do the same for the priority fee. For example, if the first transaction had a max fee of 40 gwei, the replacement must have at least 44 gwei. This rule prevents spam and wasted mempool space.
If you keep getting replacement underpriced errors, check that you are using the same nonce as the pending transaction. Also verify that you have enough ETH in your wallet to cover the higher fee, because sending a replacement with insufficient balance will also fail.
Typical steps summarized
- Open the gas tracker on Etherscan or a gas oracle site.
- Note the current base fee and average priority fee.
- Create a new transaction with the same nonce.
- Set max fee per gas above current base fee plus priority fee.
- For a replacement, bump the previous fee by at least 10%.
- Confirm you have enough ETH balance.
What this error is not
The underpriced error is not a scam. It is not a sign that your wallet is compromised. It simply means network conditions changed between when you prepared the transaction and when a validator processed it. The same transaction would likely succeed during lower congestion.
This error also does not mean you lost your gas fee. If a transaction never gets mined, you are not charged. Only executed transactions consume gas. Pending transactions that eventually fail due to being underpriced still cost nothing if they never enter a block.
Understanding these mechanics helps you set fees confidently. When network activity is high, look before you send - a quick check of current gas prices saves time and frustration.
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