Because Ethereum’s main network is approaching the new Altair network, the vast majority of nodes on the network must update their clients. According to the Nodewatch service, approximately 30% of nodes are currently out of sync.
The new Ethereum upgrade is only for validators, and it makes no difference to regular coin users. Only the beacon chain consensus mechanism is affected by the update. Contracts, in addition to users, will be unaffected by updates.
Users who act as validators must download the most recent version of their software, which can be found in the table on the Ethereum blog, and restart their nodes as usual.
If node holders do not upgrade to the latest version of the software and join the upgraded chain, they will be synced with the old chain after an Ethereum upgrade occurs. Users will be unable to receive proper rewards and realize them on exchanges while operating on an incompatible chain.
Validators on the old network will be penalized for failing to participate in the upgraded consensus in relation to the upgraded mainnet.
When the Ethereum community has decided which changes to make to the network, the changes are written by the network’s clients. The beacon chain protocol changes take effect at a specific epoch (the Altair update goes live at epoch 74240).
Any new nodes with the old ruleset will be abandoned on the old chain, unable to use new functions, participate in the current network, or use the cryptocurrency in general.