The Arbitrum network, an Ethereum L2 (Layer 2) rollup, experienced some difficulties that caused a complete stop in the production of blocks and the confirmation of transactions. According to reports from the Arbitrum team, this incident had to do with downtime regarding its sequencer, a special node that manages the order of transactions, leaving the network unusable for approximately seven hours.
Arbitration stalls for 7 hours
Arbitrum’s network, an optimistic scaling stack for the Ethereum network, came to a complete halt on January 9, leaving users unable to transact for about seven hours. The Arbitrum team informed users that the difficulties were caused by issues with their master sequencer node, which experienced a hardware failure that resulted in the network being blocked. According to Arbitrum’s documentation, the sequencer is a “specially designated full node, which has limited power to control the order of transactions.”
The Twitter account of the rollup reported the issue first, clarifying they were experiencing sequencer downtime and stating that all the funds were safe.
In a post mortem, Offchain Labs explained that there were other situations that also contributed to the situation the rollup was facing, noting:
While we generally have redundancies that would allow a backup Sequencer to seamlessly take control, these also failed to take effect this morning due to a software upgrade in process. As a result, the Sequencer stopped processing new transactions.
Problems in Rollup Land
This is not the first time that Arbitrum has faced problems with the functioning of its network. The service encountered the same type of problem in September when the sequencer also failed that time. This made the network non-operational for 45 minutes. At the time, Offchain Labs said:
The root cause of the downtime was a bug causing the Sequencer to get stuck when it received a very large burst of transactions in a short period of time. The issue has been identified and a fix has been deployed.
Although Ethereum has focused on scaling using this type of solution, the proposal has still not been well received by some users. According to For Delphi Digital, these L2 solutions “have lost market share to those of L1 in recent months, despite the migration of DeFi protocols from Ethereum”.
Even so, Arbitrum is the number one rollup solution in the Ethereum ecosystem in terms of total value locked (TVL), having launched on mainnet last August. The solution has over $2.62 billion in total value locked, according to data from L2beat, an Ethereum L2 statistics service.
