"Transaction Is Expected to Fail" — What That Error Message Means
"This transaction is expected to fail" is a warning, not a failure. Before you press confirm, your wallet quietly rehearses the transaction against a copy of the blockchain as it stands right now. If the rehearsal comes back rejected, the wallet shows you that red line. Nothing has been sent yet, nothing has been charged, and your coins have not moved anywhere.
Think of a sat-nav that checks the route before you pull away and tells you the road ahead is closed. You can still drive down it. You will just arrive at the barrier, and the fuel is spent either way.
Why does my wallet know in advance?
Every transaction that touches a protocol - a swap on Uniswap, a deposit into Aave, a mint on OpenSea - runs through a contract that checks its own conditions first. Your wallet asks the network to run those checks without recording anything, which costs nothing and takes a moment. If the contract says no during the rehearsal, it will almost certainly say no for real.
The usual reasons
- A missing or too-small approval. The protocol is not yet allowed to move that token out of your wallet.
- Not enough balance. Either of the token you are sending, or of the coin that pays the fee - ETH on Ethereum, SOL on Solana.
- The price moved. Your slippage limit is now tighter than the market, so the swap refuses itself.
- A closed sale or a sold-out mint. Common on NFT drops: the contract has simply stopped accepting.
- A token that cannot be sold. Some are written so that only the creator can sell. Buying works; selling always fails.
Should I confirm it anyway?
Usually not. The rehearsal is right far more often than it is wrong, and confirming spends the fee on a transaction the network will record as failed. The one honest exception is a fast-moving mint, where conditions change between the rehearsal and the block - and even then you are gambling the fee. Fix the cause and send a fresh transaction instead.
Check the fee coin balance first, then the approval, then slippage - in that order, changing one thing at a time. Approval troubleshooting covers the permission side, and why a transaction fails explains what happens if you confirm it regardless.