Statement regarding the recent Ethereum Classic chain reorganization

The Ethereum Classic network underwent a deep chain reorganization last night as a result of a 51% attack on the network. Parity/ OpenEthereum nodes could not correctly process the reorganization causing Parity/ OpenEthereum nodes to become out-of-sync from the main network. We are providing this information so that the ETC community and stakeholders have accurate information. We continue to investigate the issue, and we will provide more information as it becomes available.

Recommendation:

If you are a miner/pool, then ONLY use Core-geth for your Ethereum Classic nodes because Core-geth supports mining applications. Otherwise, Ethereum Classic nodes should use Core-geth or Hyperledger Besu.

• Core-geth
• Hyperledger Besu

What happened?

The miner 0x75d1e5477f1fdaad6e0e3d433ab69b08c482f14e mined ~3500 blocks offline or ~12 hours. When the miner came online it caused a large chain reorg starting at block 10904147–10907763. OpenEthereum/Parity nodes were unable to handle the large chain reorganization causing them to go out-of-sync from the network. The correct chain and heaviest chain continued with the ~3500 block reorg. The status of the nodes can be found here https://etcnodes.org/

OpenEthereum/Parity and Open-ETC no longer function properly due to an unidentified bug. The bug caused a temporary and minority chain split. In the future, any Ethereum Classic nodes operating OpenEthereum or Open-ETC could result in mining the incorrect chain.

Migrating from Parity to Core-Geth

Is the Network Secure?

The majority chain is operating as normal. The major miners unintentionally mining the incorrect chain are migrating to Core Geth as well as other ETC service providers.

Possible impact & what to do.

• Nodes: Core-geth or Hyperledger Besu
• Miners: Continue mining as the Proof of Work has chosen the chain with the block reorganization.
• Users/ Services: If you have any transactions from July 31st — August 1st, then please verify those transactions were correct.
• Please verify transactions within blocks 10904147–10907763.

For additional information, please contact ETC Core.

Other resources: https://hackmd.io/@cUBb4hAvQciAEPoU2yfrzQ/Skd4X6MZw

Statement regarding the recent Ethereum Classic chain reorganization was originally published in etc_core on Medium, where people are continuing the conversation by highlighting and responding to this story.