I am trying to reproduce the results on Remix with the smart-contract as written here: https://etherscan.io/address/0xb6ed7644c69416d67b522e20bc294a9a9b405b31#code

(for remix, go to http://remix.ethereum.org/)

The code compiles fine (with solidity ^0.4.18), however, when I try to deploy the _0xBitcoinToken contract, I get the "transaction execution failed" error. I am placing enough gas for a transaction, so that does not seem to be an issue. What am I doing wrong, and why does the error appear ?

  • Check the constructor for errors, like if a require is failing, it is making a call to an invalid address, or it is accessing an array/string without checking its length.
    – Ismael
    Jul 17, 2019 at 15:08

1 Answer 1


In Remix, there's a problem with blockhash() when using Javascript VM (https://github.com/ethereum/remix-ide/issues/1794).

If you try to deploy this contract in Ropsten, it will not fail.

So, the problem lies in line 375, which runs when the constructor is called.

challengeNumber = block.blockhash(block.number-1);

  • Thank you, I will experiment with Ropsten today, and accept if correct. Jul 17, 2019 at 16:35

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