I try to open the bitcoin-qt wallet with bitcoinj, I write this code:

private static final File WALLET_FILE = new File("C:\\Users\\Bapt\\AppData\\Roaming\\Bitcoin\\wallet.dat");

public static void main(String[] args) {
    NetworkParameters networkParameters = NetworkParameters.prodNet();

    Wallet wallet;
    try {
        wallet = Wallet.loadFromFile(WALLET_FILE);
    } catch (IOException e) {
        System.out.println("Couldn't open wallet: " + e);

    System.out.println("Balance: " + wallet.getBalance());

But I have an error:

Couldn't open wallet: com.google.protobuf.InvalidProtocolBufferException: Protocol message contained an invalid tag (zero).

So I have two questions:

  • Is is possible to do what I want ?
  • If yes, what do you think could happen here ?

Thanks for your answer.

1 Answer 1


BitcoinJ has its own wallet format, and official bitcoin client its own.

  • Ok, thank you for your answer. Is it the same for the block chain ? Could I use the block chain downloaded by bitcoin-qt in bitcoinj ? Commented Mar 18, 2013 at 13:16
  • The blockchains are different too.
    – jim618
    Commented Mar 18, 2013 at 20:43

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