A critical role/owner is transferred in a single step to a raw address. A typo sends control to an address nobody holds the key to, permanently losing admin — a two-step accept pattern prevents this.
// transferOwnership(0xABC...typo) -> admin now an unowned address, // every onlyOwner function is bricked, no recovery.
// two-step: propose then the new owner must accept
function transferOwnership(address n) public override onlyOwner { _pending = n; }
function acceptOwnership() external { require(msg.sender == _pending); _transfer(_pending); }
Largest recorded losses in the same failure class — related, not the same bug:
The SaferICO scanner runs 201 detectors over your Solidity source, SAFE-0226 among them. Paste an address or the source itself — a small per-scan fee, shown before you sign, or unlimited on any plan.