foundry-zksync book

Broadcast Limitations

These limitations apply when using cast to broadcast transactions.

No Batch Support

Batching is currently not supported on ZKsync networks, as such, any batched transactions may not be executed in order. This can often lead to failures as in the following case:

contract Calculator {
    function add(uint8 a, uint8 b) return (uint8) {
        return a+b;
    }
}

contract FooScript is Script {
    function run() public {
        vm.startBroadcast();
        Calculator calc = new Calculator();     // tx1
        uint8 sum = calc.add(1, 2);             // tx2
        vm.assertEqual(3, sum);
        vm.stopBroadcast();
    }
}

forge script script/FooTest.s.sol:FooScript ... --zksync --rpc-url https://sepolia.era.zksync.dev --broadcast 

Here the recorded transactions tx1 and tx2 would be batched as a single transaction with appropriate nonces. However, upon broadcasting to a ZKsync network, tx2 may be executed before tx1 which would cause a revert.

To circumvent this, the --slow flag may be used to sequentially send the transactions to the rpc endpoint, which keeps them in-order.

forge script script/FooTest.s.sol:FooScript ... --zksync --rpc-url https://sepolia.era.zksync.dev --broadcast --slow