Altair Upgrade Set to Activate on Ethereum Mainnet This Month

The upgrade represents a “low stakes warm-up” to prepare Beacon Chain developers and client teams for the coming Merge.

AccessTimeIconOct 5, 2021 at 4:07 p.m. UTC
Updated May 11, 2023 at 3:52 p.m. UTC
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On Oct. 27, at epoch 74240, the Altair Beacon Chain upgrade is scheduled to activate on the Ethereum mainnet.

  • According to the Ethereum blog, the upgrade represents a “low stakes warm-up” to prepare Beacon Chain developers and client teams for the coming Merge, when Ethereum will transition from a proof-of-work to proof-of-stake consensus mechanism.
  • It will provide the Beacon Chain with “light client support, minor patches to incentives, per-validator inactivity leak accounting, an increase in slashing severity, and cleanups to validator rewards accounting for simplified state management.”
  • Anyone operating a Beacon node or validator is required to update the client version to the new standard or risk being stuck on an incompatible chain.
  • Validators who do not update won’t be able to participate in the new consensus mechanism and will also face the risk of being slashed and paying penalties.
  • Because the upgrade only affects the consensus mechanism on the Beacon Chain, it will not affect end users of the current Ethereum proof-of-work blockchain.
  • In order to encourage robust code review of the Altair upgrade, the bug bounty bonus has been doubled until Nov. 27.
  • More information on how to update nodes and validators is available here.


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