Ethereum Layer 2 network Polygon’s zero-knowledge Ethereum Virtual Machine (zkEVM) chain was down for more than 10 hours over the weekend, according to data from Polygon’s block explorer.

The explorer shows a difference of around 10 hours between when two consecutive blocks were sequenced and added on to the chain.

The Polygon team confirmed the outage in an X post on March 23, noting that the issue was confined to the rollup chain, which has been in its beta version since its launch last year, with all other chains running on Polygon’s chain development kit functioning as per normal.

With a more detailed post-mortem still to come, the team revealed that the root cause of the problem was with the block sequencer during a layer 1 chain reorg. The block sequencer is responsible for packaging ordered transactions into a block. A chain reorg takes place when validators disagree on the most accurate version of the blockchain, resulting in the removal of a weaker duplicate chain.

In an update on March 25, the team said that the chain’s emergency council had activated the “emergency state” to allow the core team to fix the issue and allow the zkEVM mainnet beta chain to resume operations.

“Upon completing this upgrade, the emergency state was deactivated, meaning any further updates to the system are subject to a 10-day timelock before taking effect,” said the team on X.

Polygon’s zkEVM launched on mainnet beta in March last year,  yet data both from The Block and L2Beat shows that it has failed to gain the same amount of traction as some of its rival layer 2 ZK rollup chains in terms of transaction activity and total value locked (TVL). However, Polygon’s Proof-of-Stake (PoS) chain,  the layer 1 blockchain, saw its transactions increase 93% in the latest quarter, with TVL rising to $1.1 billion, according to data from Messari. 

“Polygon has great tech. We shouldn’t let a sequencer failure sour any reputation. It happens, bugs happen, it’s early tech,” said Nick Dodson, Fuel Network’s CEO, on X

March 25, 2024 at 05:09 am ET: The second paragraph was added to provide more clarity on the outage.