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Revert reason

In smart contracts, the revert operation triggers an exception to flag an error and revert the current call. The EVM passes back to the client an optional string message containing information about the error.

pragma solidity >=0.5.0 <0.7.0;

contract VendingMachine {
    function buy(uint amount) public payable {
        if (amount > msg.value / 2 ether)
            revert("Not enough Ether provided");
        // Alternative way to do it:
        require(
            amount <= msg.value / 2 ether,
            "Not enough Ether provided."
        );
        // Perform the purchase.
    }
}

Enabling revert reason​

Restart your GoQuorum node with the --revertreason command line option enabled. Any subsequent reverted transactions store the revert reason locally.

Where is the revert reason included​

With revert reason enabled, the transaction receipt returned by eth_getTransactionReceipt includes the revert reason as an ABI-encoded string.

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "blockHash": "0xe7212a92cfb9b06addc80dec2a0dfae9ea94fd344efeb157c41e12994fcad60a",
    "blockNumber": "0x50",
    "contractAddress": null,
    "cumulativeGasUsed": "0x5208",
    "from": "0x627306090abab3a6e1400e9345bc60c78a8bef57",
    "gasUsed": "0x5208",
    "logs": [],
    "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
    "status": "0x1",
    "to": "0xf17f52151ebef6c7334fad080c5704d77216b732",
    "transactionHash": "0xc00e97af59c6f88de163306935f7682af1a34c67245e414537d02e422815efc3",
    "transactionIndex": "0x0",
    "revertReason": "0x08c379a00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000001a4e6f7420656e6f7567682045746865722070726f76696465642e000000000000"
  }
}

Revert reason format​

As described in the Solidity documentation, the revert reason is an ABI-encoded string consisting of:

0x08c379a0                                                         // Function selector for Error(string)
0x0000000000000000000000000000000000000000000000000000000000000020 // Data offset
0x000000000000000000000000000000000000000000000000000000000000001a // String length
0x4e6f7420656e6f7567682045746865722070726f76696465642e000000000000 // String data
Example of revert reason string for: 'Not enough Ether provided'
"0x08c379a00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000001a4e6f7420656e6f7567682045746865722070726f76696465642e000000000000"