Why can a failed Ethereum transaction still cost gas?
Why can a failed Ethereum transaction still cost gas?
A failed transaction is not necessarily free.
Ethereum instructions require computing resources.
Gas measures this computational work.
A transaction can enter a block but fail during execution.
In that case, changes from the failed execution are generally reverted.
However, the cost of computation already performed is not necessarily returned.
An unsuccessful transfer can still incur fees.
Rejection before inclusion differs from failed on-chain execution.
The error message and transaction receipt help distinguish these cases.
Repeating the same operation without checking may create another cost.