Historical retrospective · Ethereum
Altair brought the Beacon Chain its first planned upgrade
Altair activated on the proof-of-stake Beacon Chain in October 2021, updating consensus rules and validator accounting before the Merge.
It gave client teams and validators experience coordinating an upgrade on Ethereum’s new consensus layer.
The event was an operational rehearsal for later changes that would affect the full network.
Consensus-layer upgrades have their own clients and failure modes; proof-of-stake operations require ongoing software maintenance.
Primary source
This retrospective summarizes the source below in original language. The displayed year refers to the dated event, proposal or specification; it is not the article’s publication date. This is not investment, legal or security advice.