About Ethereum’s Istanbul Upgrade on December 4


Danno Ferrin, ConsenSys’ Blockchain protocol engineer, proposed to activate Ethereum’s Istanbul upgrade on December 4. The targeted date means that the network’s system-wide upgrade would fall at block number 9,056,000. 

On October 25, during a core developers’ meeting, Ferrin explained that his calculation started at 14-second block times, with the network’s blocks at 245,544.5. He noted that it would climb to block 9,055,928.5 on December 4 at noon UTC. 

Reportedly, the core developers of Ethereum’s Istanbul also agreed that in case the software encounters unexpected issues prior to the scheduled date, the activation of Istanbul’s mainnet would be on hold until January 8.  

Ferrin explained the reason why the contingency plan involves more than a month. He said that if the December 4 activation would be moved, they would need to work on building a new client once again. Moreover, they would need an extension to install the new client. According to their calculation, the additional works would take at least 4 weeks. 

Notably, in the past, the core developers of Ethereum’s Constantinople, the last system-wide upgrade that was activated, encountered the same issue. Just two days before the scheduled activation, they had discovered a critical code vulnerability. As a result, they had to hold off the mainnet activation for a month. This time around, Istanbul developers want to ensure that they have covered all their bases should unexpected issues arise. 

Piper Merriam, a developer of Ethereum Foundation, said that they are doing everything they can to launch Istanbul on December 4. However, she explained that it’s critical to set an easy backstop date should something happen. 

What would happen after Istanbul?

According to a Medium post, Istanbul is the 8th in the list of Ethereum’s network upgrades. This version reportedly includes Ethereum Improvement Proposals (EIPs) that aim to align opcodes costs with their computational costs, improve the resilience of the network’s denial-of-service system, make layer 2 solutions that would ultimately enable interoperability between Ethereum and Zcash, and add more creative functions to existing contracts. 

Notably, Istanbul had hit the Ropsten and Goerli test networks last month. However, the majority of Ropsten miners said that they had encountered difficulties because the hard fork caught them off guard. According to Hudson Jameson, community manager of the Ethereum Foundation, there had been miscommunication between miners because Istanbul was released two days earlier than the planned roll-out. Many miners, as noted, didn’t upgrade to the latest software, which resulted in a split of the Ropsten network.

To avoid further confusion, Ethereum core developers introduced EIP 2124, a code change that would allow miners to identify which version of the software is running.


  1. […] Istanbul, the 8th and last hard fork to take place before Ethereum’s Serenity, had gone live last December. The process brought significant adjustments and improvements to the network. As specified on Ethereum Improvement Proposals (EIPs), the Istanbul upgrade paved the way for enhanced interoperability between the network and the Zcash (ZEC) Blockchain. Furthermore, the hard fork also resulted to the optimizations of Aztec and ZEther’s cryptography procedures. […]

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