    function upgrade(ProposedUpgrade calldata _proposedUpgrade) public virtual returns (bytes32 txHash) {
        // Note that due to commitment delay, the timestamp of the L2 upgrade batch may be earlier than the timestamp
        // of the L1 block at which the upgrade occurred. This means that using timestamp as a signifier of "upgraded"
        // on the L2 side would be inaccurate. The effects of this "back-dating" of L2 upgrade batches will be reduced
        // as the permitted delay window is reduced in the future.
        require(block.timestamp >= _proposedUpgrade.upgradeTimestamp, "Upgrade is not ready yet");

        _setNewProtocolVersion(_proposedUpgrade.newProtocolVersion);
        _upgradeL1Contract(_proposedUpgrade.l1ContractsUpgradeCalldata);
        _upgradeVerifier(_proposedUpgrade.verifier, _proposedUpgrade.verifierParams);
        _setBaseSystemContracts(_proposedUpgrade.bootloaderHash, _proposedUpgrade.defaultAccountHash);

        txHash = _setL2SystemContractUpgrade(
            _proposedUpgrade.l2ProtocolUpgradeTx,
            _proposedUpgrade.factoryDeps,
            _proposedUpgrade.newProtocolVersion
        );

        _postUpgrade(_proposedUpgrade.postUpgradeCalldata);

        emit UpgradeComplete(_proposedUpgrade.newProtocolVersion, txHash, _proposedUpgrade);
    }
