Errors

Solidity typically uses require, revert, and string messages. Move typically uses assert! with numeric codes, often wrapped by the error module for better context.

Solidity

function onlyOwner() external {
    require(msg.sender == address(1), "Contract: not owner");
}

Move

use std::error;
use std::signer;

const ENOT_OWNER: u64 = 1;

entry public fun only_owner(owner: &signer) {
    assert!(
        signer::address_of(owner) == @0x1,
        error::permission_denied(ENOT_OWNER)
    );
}

The practical migration difference is that Move errors are designed to be machine-stable first and human-readable through docs, constants, and surrounding context.