After a failed attempt to agree on a deadline for the proposed hard fork, which was supposed to be officially announced on Oct. 31, Ethereum developers have now chosen Tuesday Nov. 22, 2016 for the next and fourth hard fork.

The Spurious Dragon hardfork is scheduled for block 2675000, which will likely occur between 15:00 and 16:00 UTC Tuesday evening (CET), a post on the Ethereum platform says.

The post says:

“The block number for the testnet “Morden” was scheduled at block 1885000…

Performing the fork in the test network prior to performing it in the main network was an important measure taken in the testing process to ensure a smooth rollover into the post-fork state.

The Morden fork occurred on Nov-20-2016, 06:12:20 +UTC, at block 1885000 as planned. A bit later, at block 1885074, there was a consensus issue between Geth and Parity.”

Since late September, there has been an increasing number of denial-of-service attacks that targeted the Ethereum network by spamming the network. Despite the release of several Geth - the Golang implementation of the Ethereum protocol - and Parity updates, the Ethereum network continuously failed to deal with the intensity of ongoing DoS attacks, which ultimately forced the foundation to execute a hard fork.

Why hard fork the network?

The post says that while the previous hard fork - a.k.a “Tangerine Whistle” - addressed immediate network health issues due to the DoS attacks, the upcoming “Spurious Dragon,” which is the second hard fork of the two-round hard fork response to the DoS attacks on the Ethereum network in September and October, will address: “important but less pressing matters such as further tuning opcode pricing to prevent future attacks on the network, enabling “debloat” of the Blockchain state, and adding replay attack protection.”

It adds that all issues found during the rollout of Spurious Dragon on the test network were Morden-specific and there are currently no known issues affecting the Mainnet.

Some of the highlighted Ethereum Improvement Proposals (EIPs) that describe the protocol changes implemented in this hard fork, include EIP 155: Replay attack protection which prevents transactions from one Ethereum chain from being rebroadcasted on an alternative chain; EIP 160: EXP that adjusts the price of ‘EXP’ opcode so it balances with the computational complexity of the operation; EIP 161: which makes it possible to remove a large number of empty accounts that were put in the state at very low cost as a result of earlier DoS attacks; and EIP 170 for contract code size limit.

Users are expected to download the latest version of Ethereum client as the upcoming hard fork will make an outdated client sync to the pre-fork Blockchain once the fork occurs, which will make the user stuck on an incompatible chain following the old rules and unable to send ether or operate on the post-fork Ethereum network.

Also, any transactions a user makes will still be susceptible to replay attacks.

After the announcement for the last hard fork, Ethereum wallet service provider and trading platform Coinbase, as well as Kraken, warned their users of likely network instability and decided to suspend ETH transactions briefly.