When I try to interact with the contract with web3.py, I am using ganache, I get the completely useless error message:

ValueError: {'message': 'execution error: revert', 'code': -32000, ... , 'name': 'Error'}

It works correctly when using remix. This is my python code:

w3.eth.defaultAccount = w3.eth.accounts[0]
exams_contract = w3.eth.contract(abi=abi, bytecode=bytecode)
exams = w3.eth.contract(
tx_hash3 = exams.functions.studentAddExam(w3.eth.accounts[1]).transact()

And my solidity code:

function studentAddExam(address studentAddress) public returns (string memory returnString){
    // Receives a student's address and adds it to the people that passed that exam
    // Only the creator of the exam can do this
    string memory professorsExamHash = professorsExam[msg.sender];  // The hash of the exam owned by msg.sender
    Exam storage examObj = examHash[professorsExamHash];
    examObj.examSuccess[studentAddress] = true;
    return professorsExamHash;

I can interact with the contract using other functions.

1 Answer 1


Hope this helps someone. The error was in the ABI or in the Bytecode. I replaced it and it worked.

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