When swapping on a DEX with Coinbase Wallet, here are some troubleshooting steps that may be helpful.
Swap simulator and why it says your transaction is likely to fail
Swap simulator is a Coinbase service that runs Hardhat. Hardhat replicates an on-chain transaction, but doesn't commit it to chain. This means it can tell us when a transaction is likely to fail without actually submitting it. We protect customers from failed transactions before they submit them.
The simulation runs the transactions against a finalized blockchain state. Depending on the chain, this could be 5 blocks to 30 blocks away from tip. Typically simulation occurs approximately 60 seconds behind tip so it doesn't have to deal with reorgs.
Simulator itself doesn’t check anything; it creates a fork environment (facilitated with Hardhat) that executes the transaction and outputs the result. We report running the transaction outcome and pass it back; be it an error or success.
A swap can fail because of a sudden shift in the exchange price between the cryptocurrencies you’re trying to swap. We recommend waiting at least 60 seconds before retrying the transaction.
If you continue to encounter this error, please restart the Coinbase Wallet app and make sure you’re running the most up-to-date version.
Swap showing up as pending
Network congestion and/or paid gas fees that are lower than the current network average may be the reason your swap is still in pending status.
Ethereum miners prioritize transactions with the highest paid gas fees. If your transaction has a lower paid gas fee, then your transaction confirmation on the blockchain gets pushed to the bottom of the queue.
As a result, your transaction may become stuck as more transactions with higher paid gas fees are added to the network pool.