Ethereum just transitioned its oldest test network Ropsten to proof of stake in a ‘very big event’ for the merge and the crypto space

Ropsten, the oldest Ethereum test network, transitioned to proof of stake on Wednesday in a milestone moment for the cryptocurrency space.

Though it will take time for developers to assess how it went, this is a huge trial ahead of the real Ethereum “merge” upgrade slated for this summer, which is supposed to make the chain more eco-friendly and efficient.

Currently, Ethereum relies on a proof-of-work model, where miners race to complete complex puzzles to validate transactions. This requires a lot of computer power and energy. The real merge will shift Ethereum to proof of stake, as Ropsten did today during its test upgrade. In proof of stake, transactions are validated by those who contribute, or “stake,” to the network instead. This would dramatically decline the amount of energy used on Ethereum.

That’s why the Ropsten merge test is a “very big event,” Superphiz, a pseudonymous Ethereum community consultant, said during a Ropsten network upgrade countdown call on Wednesday.

Tests in preparation of Ethereum’s main network merge are key, developers say. There’s a lot riding on the real merge with a lot of money at stake, as Ethereum is arguably the most used blockchain and its ecosystem is relied on heavily.

Ropsten merge

It will take a few hours for developers to understand whether the upgrade happened without issues, Superphiz said. But it will show how ready the networks are for the merge, which is very important.

“We're hoping it’s going to be a good demonstration of just how far we've come. If everything goes well, it basically means that we're just a bit of polishing away from the merge being able to happen on mainnet,” Ethereum cofounder Vitalik Buterin said on the call.

Ropsten is seen as the test network most like the main Ethereum network, which will be helpful for assessing what might come up during the real merge.

Even if the real merge has hiccups, Ethereum developers will get “back on our feet,” Buterin said. “So, I think it's actually important to not be a catastrophist about the actual events, and also be mindful about the risks that do still remain after the events.”

Buterin previously predicted that so long as all goes well with the Ropsten test merge, the real Ethereum merge will happen in August.

This story was originally featured on Fortune.com