Ethereum Constantinople Upgrade Announcement | Ethereum Foundation Blog

Note: Constantinople is postponed due to security vulnerabilities. Please ignore the instructions in this blog post. Click here for more information.

The Ethereum network will undergo planned upgrades at the following times: Block number 7,080,000is predicted to occur. Wednesday, January 16, 2019. The exact date may change depending on the current and subsequent block times and may be valid for 1-2 days before or after. You can find the countdown timer here: Monitor network upgrades in real time.

What is Constantinople?

Constantinople is the name given to this network upgrade. Previous network upgrades had different names: spurious dragon and byzantium.

Do I need to do anything as an Ethereum user or Ether holder?

If you use an exchange (such as Coinbase, Kraken, Binance), a web wallet service (such as Metamask, MyCrypto, MyEtherWallet), a mobile wallet service (such as Coinbase Wallet,, Trust Wallet), or a hardware wallet (such as Ledger, Trezor, KeepKey, etc.), you do not need to do anything unless your exchange or wallet service tells you to take additional steps.

What should a node operator or miner do?

Download the latest version of the Ethereum client.

What if I’m a miner or node operator and don’t participate in the upgrade?

If you are using an Ethereum client that has not been updated to the latest version (above), your client will sync to the pre-fork blockchain once the upgrade occurs. You will remain on an incompatible chain following the old rules and will not be able to send Ether or operate on the upgraded Ethereum network.

What is Ethereum Land Network Upgrade?

Network upgrades involve changing the underlying Ethereum protocol and creating new rules to improve the system. The decentralized nature of blockchain systems makes network upgrades more difficult. Network upgrades on blockchain require collaboration and communication with the community as well as developers from various Ethereum clients to ensure a smooth transition.

What happens during a network upgrade?

After the community reaches a consensus on which changes should be included in the upgrade, changes to the protocol are written to various Ethereum clients such as geth, Parity, and Harmony. Protocol changes become active at specific block numbers. Nodes that are not upgraded to the new ruleset are destroyed on the old chain where the previous rules still exist.

What changes are occurring in Constantinople?

Changes implemented in Constantinople are defined using the EIP. Ethereum Improvement Proposals (EIPs) describe standards for the Ethereum platform, including core protocol specifications, client APIs, and contract standards. The following EIPs will be implemented in Constantinople.

EIP 145: EVM bitwise shift instructions

  • Provides native bitwise shifts at a cost comparable to other arithmetic operations.

  • EVM does not have a bitwise shift operator, but other logical and arithmetic operators are supported. Shift operations can be implemented via arithmetic operators, but they are more expensive and take longer to process. The SHL and SHR implementations using arithmetic operations cost 35 gas each, while these proposed instructions cost 3 gas.

  • In other words, this EIP adds native functionality to the protocol, making it cheaper and easier to do certain things on-chain.

EIP 1014: Skinny CREATE2

  • Add a new opcode to 0xf5. It takes four stack arguments: endowment, memory_start, memory_length, and salt. Works the same as CREATE, except using keccak256( 0xff ++ sender_address ++ Salt ++ keccak256(init_code))).[12:] instead of keccak256(RLP(sender_address, nonce))[12:] as the address where the contract is initialized.

  • This allows you to interact with addresses that are not already on the chain, but you can only rely on the possibility that it will eventually contain code created by a particular piece of init code.

  • Important for state channel use cases that involve counterfactual interactions with contracts.

  • In other words, this EIP allows you to work with addresses that have not yet been created.

EIP 1052: EXTCODEHASH opcode

  • This EIP specifies a new opcode that returns a keccak256 hash of the contract’s code.

  • Many contracts need to perform checks on the contract’s bytecode, but do not necessarily require the bytecode itself. For example, a contract may need to check whether another contract’s bytecode is one of a set of allowed implementations, or it may perform an analysis of the code and if the analysis is successful, the bytecode is We may whitelist matching contracts.

  • Currently, contracts can do this using the EXTCODECOPY opcode, but this is expensive, especially for large contracts when only the hash is needed. As a result, a new opcode called EXTCODEHASH has been implemented that returns a keccak256 hash of the contract’s bytecode.

  • In other words, this EIP allows certain tasks to be performed on the chain more cheaply (less gas required).

EIP 1283: Net Gas Metering for SSTORE without Dirty Maps

  • This EIP proposes changes to the net gas metering of the SSTORE opcode to enable new uses for contract storage and reduce excess gas costs that are inconsistent with the mechanics of most implementations.

  • In other words, this EIP makes it cheaper (requires less gas) to do certain things on the chain, especially things that are currently “excessively” expensive.

EIP 1234: Constantinople difficulty bomb delay and block reward adjustments

  • Average block times are increasing as difficulty bombs (also known as “Ice Age”) are slowly accelerating. This EIP of his proposes delaying difficulty bombs by about 12 months and reducing block rewards to adjust for ice age delays.

  • In short, this EIP ensures that the blockchain is not frozen before proof-of-stake is ready and implemented.

thank you!

A big thank you to the Ethereum community and to all the clients and all Ethereum developers on the platform who came together to provide input, thoughts, and contributions. Thanks to Reddit user cartercarlson for permission to use it. his reddit post And that mycrypt Teams that used “”Ethereum Constantinople: Everything you need to know“Medium post.

Disclaimer: This is an emerging and evolving highly technical field. If you implement the recommendations in this post and choose to continue participating, be sure to understand how it will affect you. You should understand that risks include, but are not limited to, unexpected bugs. By choosing to implement these recommendations, you assume sole risk of the consequences. This post and recommendation is not a sale of any kind. We also do not create any warranties of any kind, including but not limited to those related to the Ethereum Network or Ethereum Clients referenced herein.

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