XRP Ledger Is Back on Track After Temporary Halt

XRP Ledger network temporarily stopped progressing earlier today

The XRP Ledger stopped processing transactions for about 15 minutes earlier today, according to developer Wietse Wind.

Update: it lasted not 2 minutes (my original Tweet) but 15 minutes. At the time of Tweeting (because I have decent monitoring and was warned straight away) the counter was at 2 minutes missing forward progress.

Also: 4 validators down: this was caused by a lot more being down.

— WietseWind – 🛠 XUMM @ XRPL Labs (@WietseWind) November 3, 2021

Each protocol server relies on its own unique node list (UNL) to validate new registers.

The quorum requirement is set at 80%. If more than 20% of validators fail to reach consensus or remain unavailable, the network is unable to confirm new transactions.

As explained by Wind, four validators were down, which caused the quorum to drop below the required threshold.

The average close time for a new ledger is about four seconds, but the validators were unable to reach an agreement, which stopped processing transactions.

This is what the ledger close times look like (courtesy of @Silkjaer). From UTC 12:25 » 12:48 validators couldn't agree on what should have been included in the next ledger. pic.twitter.com/MJMD4Bb2lh

— WietseWind – 🛠 XUMM @ XRPL Labs (@WietseWind) November 3, 2021

The XRP Ledger Foundation claims that the accident did not result in a loss of any transactions.

As we are aware the XRPL choses safety over liveliness. There was a temporary halt in ledgers closing. There were no ledgers dropped, or holes created. Validators are proposing now, nodes are active and the network is back on track with no intervention.

— XRP Ledger Foundation (Official) (@XRPLF) November 3, 2021

Wind says the network is now working fine after a sudden shutdown:

Finally: your XRP is safe. No history is lost, the XRPL is working. I believe we need more proactive infrastructure operators.

Ripple’s CTO David Schwarz has supported the implementation of the negative UNL feature, which ensures that the network can keep moving even when multiple validators are down. In this way, transactions would continue being confirmed during a temporary outage:

We need to deploy the negative UNL functionality. More validators is also good, but has some of its own tradeoffs.