The most common cause is the price moving outside your slippage tolerance before
the trade settled. Request a fresh quote and try again. If it keeps happening in
fast-moving conditions, a slightly higher slippage tolerance can help.
The first time you sell a given token, you may need a one-time onchain approval
before the trade can proceed. Approve the prompt in your wallet, then continue.
A direct trade needs enough of the chain’s native token to cover the network fee.
Add native token to your wallet, or use gasless trading where available so the
relayer covers the fee.