Once the date is voted on by developers and confirmed via GitHub, slot 6209536, occurring on or around April 12, will be set in stone for the Shanghai upgrade. This means that Shanghai will be slightly delayed from the developers initial target for this month.
When Ethereum switched to a PoS consensus mechanism in September in an event known as the Merge, the network began using validators instead of miners. Validators had to stake 32 ETH in order to approve or add blocks to the blockchain.
Before validators joined Ethereum’s PoS blockchain, they were made aware that their staked ETH and any rewards would remain locked up until Shanghai. Some validators have had their funds locked up since December 2020, when Ethereum’s PoS Beacon Chain went live.
Now, those validators will be able to decide after April 12 what they want to do with their stake.
Since the Merge, Ethereum developers have run numerous tests in order to ensure that staked ETH withdrawals would function properly. All three tests on Ethereum’s testnets ran smoothly, though the last testnet hard fork on Goerli experienced low participation rates because validator nodes didn't upgrade in time.
While staked ETH withdrawals were able to be processed on the testnet, blocks weren't completed until about 90 minutes after the fork went live.
Ben Edgington, product lead of Teku, an Ethereum client, told CoinDesk that “despite the reduced participation, we could see that all client types were producing valid blocks, and that participation increased over time. This reassured us that nothing was fundamentally wrong, just late upgraders.”
Edgington added that “losing finality for 90 minutes is inconvenient, but not critical for most applications or users of Ethereum.”
Ethereum developers aren't worried that this will happen on the mainnet too. “It's quite typical for testnet upgrades to be a little bumpy, but people are very diligent about maintaining their mainnet staking infrastructure,” Edgington said.
UPDATE: March 16, 2023, 14:29 UTC: Adds target epoch number.
CORRECTION: March 16, 2023, 19:04 UTC: Shanghai's target is slot 6209536, not epoch 6209536.
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