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About Qtum and Mainnet Ignition

Qtum is a decentralized blockchain project built on Bitcoin's UTXO model, with support for Ethereum Virtual Machine based smart contracts, and secured by a proof of stake consensus model. It achieves this through the revolutionary Account Abstraction Layer which allows the EVM to communicate with Qtum's Bitcoin-like UTXO blockchain. For more general information about Qtum as well as links to join our community, go to

Welcome to the Qtum Ignition Main Network. This is the main network where the tokens hold value and should be guarded very carefully. There will be a testnet setup soon for developers, in the meantime you can use -regtest mode for testing needs. We will announce details about the token swap from QTUM ERC20 coins to QTUM mainnet tokens soon, watch our website for details about that.

The major features implemented in Qtum Ignition include:

  1. The Ethereum Virtual Machine, which allows for compatibility with most existing Solidity based smart contracts.
  2. The Smart Staking Protocol is complete, which is an optimized Proof of Stake implementation designed for a smart contract platform (however, smart contracts can not participate in staking yet).
  3. An early and basic smart contract GUI has been implemented that can be used for creating contracts, sending data and Qtum to them, and checking their status by executing them locally. This functionality is similar to Mist's UI right now, but it is still an early version. We will be working on this more to improve it.
  4. Regtest mode, which is ideal for developers who wish to create their own private blockchain. It is tuned specifically to make development easier. It will stake blocks automatically every 30 seconds, and can generate proof-of-work blocks instantly as needed.
  5. The Decentralized Governance Protocol is completely implemented and functional, which allows certain network parameters to be modified without a fork.

For more technical information for how to start developing with Qtum please read the Guide and also see this tutorial for deploying a simple faucet smart contract (it hasn't yet been updated for Mainnet for obvious reasons, but all the instructions are the same and you can try them in regtest mode)

Note: Qtum Core is considered beta software. We make no warranties or guarantees of its security or stability.

Update History

  • v0.16.2 - Recommended update - Improved network security and bug fixes
    • Implement network spam protection
    • Only request blocks from peers when their chainwork is strictly greater than the current tip
    • Add extra header checks for PoS timestamp, block indexes, signature type (LowS), synchronized and rolling checkpoints.
    • Add recent checkpoints
    • Update nMinimumChainWork, defaultAssumeValid and chainTxData
    • Fix failing Qt tests in make check on OSX Mojave
    • Fix getblocktemplate rpc call for PoS blocks
    • Fix help messages for walletpassphrase and getnetworkhashps rpc calls
  • v0.16.1 - Mandatory Update - Critical bug fix
  • v0.16.0 - Upgrade Qtum core to bitcoin core 0.16 and bug fixes
    • Upgrade Qtum core to bitcoin core 0.16 including segwit wallet, bech32 addresses, HD-wallets by default and more
    • Fix a bug where contract transactions with no change would fail in some cases
    • Fix a display bug where multiple logs would not show corretly in Qt wallet
    • Update gitian build scripts to support ubuntu bionic as building host
  • v0.15.3 - Recommended update - Bug fix
    • Fix a bug with searchlogs and waitforlogs rpc calls that caused duplicacte logs to show in some cases
    • Add support for building with boost 1.67
  • v0.15.2 - Recommended update - Improved seeding and bug fixes
    • Fix a staker halving subsidy calculation bug
    • Fix some translations errors and typos
    • Add Support for openssl 1.1
    • Fix CVE-2018-12356 by hardening the regex
    • Fix a python tests bug that caused bulk running of tests to fail
    • Add static seeds
    • Add new dns seed nodes
    • Update copyright year
  • v0.15.1 - Upgrade Qtum core to bitcoin core 0.15.1 and bug fixes
    • Upgrade Qtum core code to bitcoin core 0.15.1 with important performance improvments and other features, read more about bitcoin core 0.15.0 and 0.15.1
    • Fix a bug with reindexing when the data directory is empty
    • Prevent sending QRC20 tokens to P2SH Qtum addresses in the Qt wallet
    • Restore JS number as string support for callcontract and sendtocontract rpc calls
    • Fix a bug where the wrong block hash would be stored in the transaction receipt for miners with -logevents enabled
  • v0.14.16 - Improvments and Bug fixes
    • Fixed a bug where transactions with low fees would get stuck in the local mempool.
    • Fix a bug with clearing cache of StorageResults
    • Add contract support to "createrawtransaction" rpc call
    • Add sender support to "sendtoaddress" rpc call
  • v0.14.15 - Recommended Update
    • Add EVM global variables to callcontract
    • Update gitian build script
    • Update CentOS build instructions
    • Add exception data to TransactionReceipt
    • Fixed a bug where the gas price could not be parsed correctly on certain platforms (reported by APIS)
    • Fixed a bug where the logs were not reverted on disconnect block in certain cases
  • v0.14.14 - Mandatory Update
    • New Qt GUI
    • Fix Qt wallet freeze when syncing from scratch with -logevents or -reindex
    • Fix a bug with cacheUTXO (hardfork at block 100000 in mainnet, 84500 in testnet)
    • Add update checking functionality to Qt wallet
    • Fix a bug in token transfers history dates
    • Fix a bug with searchlogs rpc call
    • Add an extra check when adding token addresses
    • Fix compatibility with boost 1.66
    • Add checkpoints
    • Update nMinimumChainWork and defaultAssumeValid chain params
    • Add minmempoolgaslimit startup argument
    • Add Gitian build signatures
  • v0.14.13 - Mandatory Update
    • Fix a callcontract bug which in very specific cases could cause the node to fail to sync the blockchain
    • Add ability to save and restore contract addresses and ABI data
    • Make the token confirmation view data correct
  • v0.14.12 - Recommended Update
    • Added option to disable change address usage
    • Fixed bug where heavy RPC usage could cause the wallet to crash
  • v0.14.11 - Optional Update
    • Changed our versioning scheme to be consistent and avoid the two version number confusion
    • Add feature to restore wallet in the Qt wallet
    • Add new RPC call "waitforlogs" that is particularly useful for Dapp developers
    • Add long-polling support to the gettransaction RPC call
  • v1.1.4 - Recommended update
    • Fixed a bug that would cause syncing to stop
    • Fixed a bug that would cause the wallet to crash when using -logevents
  • v1.1.3 - Highly recommended update
    • Fixed a bug that caused contact addresses to show in receive token address dropdown
  • v1.1.2 - Optional update, but recommended if using QRC tokens
    • Fixed a bug with token transactions where the transaction ID displayed was incorrect in the Qt wallet
    • Allow adding 0 balance addresses as the token receiver in the Qt wallet
  • v1.1.1: When sending to contracts, the sender address is now the default change address to reduce confusion; fix -salvagewallet so it works with token transactions
  • v1.1.0: Add GUI support Qtum QRC tokens, allowing full management of tokens on the Qtum blockchain from the Qt wallet
    • Sending to a contract no longer requires ABI data, allowing easy participation in simple crowdsale contracts
  • v1.0.4: Fix bug where certain circumstances when staking could cause the displayed balance to be inaccurate until completely redownloading the blockchain.
  • v1.0.3: Fix staker bug that reported false messages; slightly increases staking performance; optimize staker parameters; fix white send button in GUI
  • v1.0.2: Various UI fixes, minor gas overflow consensus fix, per-txout exploit fix, testnet mode setup and functioning
  • v1.0.1: Fixed network magic bytes and minimum version to ensure the main network does not conflict with the Skynet network
  • v1.0: Initial release

Reindex Required When Upgrading from v1.0.1

When you first start the Qtum 1.0.2 GUI wallet after using Qtum v1.0.1 it will prompt you that it must reindex the database. This is normal and is a result of switching our internal database format from per-transaction to per-txout. If you use qtumd -daemon it will silently fail to start. You need to use qtumd -daemon -reindex in this case.

Qtum Documentation and Usage Resources

Basic usage resources:

Development resources:

General Info about Qtum:

Build Qtum Core

If you want to build it from source, it's recommended to follow the specific "build" documentation for your platform. But mostly it boils down to the following:

  1. Clone the qtum source code and cd into qtum

     git clone --recursive
     cd qtum
  2. Build qtum-core:

    Configure and build the headless qtum binaries as well as the GUI (if Qt is found).

    You can disable the GUI build by passing --without-gui to configure.

  3. It is recommended to build and run the unit tests to ensure everything is working correctly:

    make check

If you encounter an error like:

make[2]: *** No rule to make target ‘cpp-ethereum/utils/libscrypt/b64.c’, needed by ‘cpp-ethereum/utils/libscrypt/libbitcoinconsensus_la-b64.lo’. Stop.

Then you did not checkout the cpp-ethereum submodule for Qtum. To do that, simply:

cd qtum
git submodule update --init --recursive

Validate and Reproduce Binaries

Qtum uses a tool called Gitian to make reproducible builds that can be verified by anyone. Instructions on setting up a Gitian VM and building Qtum are provided in doc/

Community Resources

Make sure to check out these resources as well for more information and to keep up to date with all the latest news about Qtum. At least 1 developer is always around, so if you're developing on Qtum and need help, we'd love to welcome you to our community.

Qtum Smart Contract Limitations

  • EVM smart contracts can not receive coins from or send coins to any address type other than pay-to-pubkeyhash (starts with Q) addresses. This is due to a limitation in the EVM
  • Contracts are not allowed to create contracts with an initial endowment of coins. The contract must first be created, and then be sent coins in a separate transaction. Humans are also not allowed to create contracts with an initial endowment of coins.
  • Although all of the infrastructure is present, Qtum Core does not currently parse Solidity event data. You must parse this yourself using either searchlogs or -record-log-opcodes features.
  • It is not possible to send a contract coins without also executing the contract. This is also the case of Ethereum. This was promised in earlier discussions and technically does work, but due to lack of time for testing this feature was disabled. We hope to reenable this feature with release of the x86 virtual machine in 2018.
  • In Qtum there can be multiple addresses used to create a proof-of-stake block. However, the EVM can only see the first output using the coinbase operation in Solidity (this address is also the one registered for the continuous staker rewards after 500 blocks).

Hash Validation

If you would like to validate that the binaries you download are exactly the same as those provided and built by the Qtum team, then you can compare your binaries to the following sha256sum hashes:

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2748be76522fe4b14781ca21c5ae9c58fca95a3e0423f83e5c2f8f9b16b49330  qtum-0.16.2-osx-unsigned.dmg
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b4c6b0de4c8ccb4c56ebba59e8fb189608df414f836011888fc4809eef902b3a  src/qtum-0.16.2.tar.gz
bcb2ec4badab2f5a0168c285090808a6f5d2d51f78a2adf4efe235eccbe10dea  qtum-osx-0.16-res.yml