What Happens If There Is a Bug in a Smart Contract’s Code?

Due to the immutable nature of blockchains, a bug in a deployed smart contract's code is permanent and cannot be directly fixed. This can lead to significant consequences, including the permanent loss of funds or the contract becoming non-functional.

The most famous example is the DAO hack, where a vulnerability was exploited to drain millions of dollars. The only way to address a critical bug is often to migrate to a new, corrected contract or, in extreme cases, to perform a hard fork of the entire blockchain to reverse the effects of the bug.