Ropsten, the testnet for the Ethereum network, has forked into two separate chains after the Istanbul upgrade was activated. Originally, the upgrade was set to go live on the Ropsten Testnet on Oct. 2 at block height 6,485,846, but unusually fast block confirmation times led for the update to arrive on Sep. 30—two days ahead of schedule.
The issue was first reported on Gitter as a problem that caused a Geth Ethereum client to be stuck at the hard ford block, but later reports confirmed that users from other clients were also experiencing the same problem.
Hudson Jameson, community manager at the Ethereum Foundation, explained the situation: “It appears there are two different chains mining the Ropsten test network. There are miners mining on the old [Ropsten] chain and miners mining the new one.”
Network-wide upgrades of Proof-of-Work blockchains such as Istanbul require miners to manually upgrade the software, which didn’t happen because of Istanbul occurring before it was anticipated. Because a large group of miners failed to upgrade to the newest version, the network was forked into two separate chains. The only solution to the problem is to have remaining miners update their software to the newest version.
Jameson also took to Twitter to weigh in on the situation:
A similar incident occurred during the upgrade to Constantinople, the previous system-wide update to the Ethereum network. Once again, this problem was caused due to coordination issues between miners.
The activation of Istanbul’s testnet will be discussed in a core developer call on October 4th.