Ethereum’s tenth "shadow fork" went into effect Tuesday, 26 hours earlier than expected, as the network continues to run tests ahead of the anticipated shift from using the energy-intensive proof-of-work protocol to proof-of-stake. In preparation, Ethereum has been undergoing a series of test, or shadow, forks, which copy data from the main network (mainnet) to a test environment network (testnet).

The fork occurred at 11:45 UTC (7:45 a. m. ET) when Terminal Total Difficulty (TTD) was overridden at 54,892,065,290,522,348,390,492 at block 15217902.

The shadow fork brings the project one step closer to Ethereums mainnet upgrade in September. The third and final testnet merge, Goerli, is expected to happen Aug. 10.

Ethereum DevOps Engineer Parithosh Jayanthi told CoinDesk that this shadow fork will test releases that approximate the releases that will be used in the Goerli merge. As for why it happened earlier than expected, Jayanthi said there was a clear change in the hashrate, or computational power, that could have sped up the process. This will not be the last mainnet shadow fork, and Ethereum will continue to run mainnet shadow forks until the Merge.

No significant glitches were reported. Read more: Merge Testing on Ethereum: What Is It and Why Does It Matter?.