Transactions on the Ethereum network are validated thanks to a consensus of miners. They can clear very fast, take a long time, or even fail. This page helps you understand why that happens.
On the Ethereum network, everything starts by submitting a transaction - which can then succeed, fail or be replaced:
Submitted: the transaction is ready to be picked up by the miners and broadcasted on the blockchain (if valid).
Success: the transaction cleared - there is no going back.
Failed: the transaction failed because it was not valid - see more below.
Canceled, Replaced, Dropped&Replaced: the transaction was canceled or replaced by another, see more below
Gas Cost Incurred & Status
Expected cost (not paid yet)
Actual Gas Cost (lower than expected)
The gas cost is still incurred
Canceled or Replaced
No gas cost incurred
If the gas price of a given transaction is too low to be picked up within a reasonable amount of time, your swap will most likely fail because the price changed.
Depending on the specifics of your trade, ParaSwap can secure a minimal expected price only for so long - we recommend defaulting your transaction to a fast gas price to avoid any risk of failure.
Transactions can fail for various a range of other reasons, such as invalid input parameters.
On top of all their other parameters, Ethereum transactions are submitted with a "nounce". The nounce represents the order of transactions made by an address - it increases with each transaction.
Several transactions can be submitted on the same as long as no transaction was cleared on that nounce yet. In such a case, once the first transaction succeeds (most likely the one with the highest gas price), all others will be "dropped and replaced".