XRP Ledger's hour-long halt sparks debate over consensus tradeoffs

XRP Ledger experienced a temporary transaction outage of approximately 64 minutes late Tuesday, halting at ledger height 93,927,173 and prompting debate between critics and proponents over its severity.

Some argued that the XRP Ledger halting for over an hour represented a consensus failure, opening up the network to critical coordinated attack vectors, and criticized a perceived level of centralization between a relatively small number of trusted validators.

In response, CTO of blockchain infrastructure firm Eminence Daniel Keller said the halt was “working as designed” to ensure the integrity of the ledger. “There are tradeoffs with every solution. Pausing until a solution is found is one of them,” he said. “It's validate or bust.”

However, Keller acknowledged that the incident wasn't ideal. “The network couldn't reach consensus on a specific ledger, that's why no new ledger was pushed. There is something wrong, we will have to figure out what and fix it.”

XRP Ledger incorporates a halt as an outcome of its consensus mechanism. When more than 20% of the network's UNL validators disagree, the system temporarily halts to prevent issues like double-spending and ledger inconsistencies. The safety mechanism allows for automatic recovery once validators can align their UNLs, Ripple CTO David Schwartz explained in 2021.

“It's like if you invented a technology that would make it less likely for a nuclear reactor to melt down,” Schwartz said at the time. “Nobody in the nuclear reactor industry wants to talk about how bad a meltdown is. They want to pretend that they don't exist. But let's be honest, blockchains have failure modes … and I think it is important that we continue to innovate to reduce the odds of them happening and reduce their severity, even if it is a bit embarrassing for the industry to point the finger at [them]. There is a residual failure mode in the XRP ledger, which is if too many validators fail before humans can respond to it, the ledger could halt its forward progress.”

XRP Ledger has a network of over 200 validators in total. However, there are a much smaller number of validators on Unique Node Lists (UNLs) that each node trusts to participate in the consensus process. The XRPL Foundation's recommended Unique Node List (UNL) includes at least 35 validators. In contrast, though not directly comparable, there are over 1 million active validators on Ethereum, while Bitcoin has a network of at least 65,000 nodes and thousands of miners globally.

Though Keller made the false analogy of Bitcoin users sometimes having to wait a similar amount of time for transactions to confirm, Bitcoin has experienced its own downtime in the past following the value overflow incident in 2010 and a network split bug in 2013. Ethereum was temporarily paused following The DAO hack of 2016 to implement a hard fork that reversed its effects, and Solana , TON , Avalanche and Sui are also among blockchain networks that have experienced outages or disruptions in recent years.

XRP Ledger previously suffered a node crash in November 2024, with the network unable to process transactions for around 10 minutes. 

No loss of user funds, cause under investigation

Initially joking about the incident with a meme that said, “Hello, IT, have you tried turning it on and off again,” David Schwartz, CTO of XRPL developer Ripple, later confirmed the network had recovered, with transactions processing as normal, though the root cause is not yet known.

Outlining his preliminary observations, Schwartz explained that the network had experienced a “drift” where consensus was running, but validations were not being published, causing the network to fragment. Validator operators manually intervened to select a stable starting point after the last fully validated ledger and resumed publishing validations. Once validations from a few sources were received, consensus was regained and the network synchronized, he said.

However, Schwartz later clarified that very few UNL validators actually made any changes, so it was possible the network had “spontaneously recovered” automatically. “It looks like, as far as we can tell, only one validator operator manually intervened. It's still not entirely clear if that solved the problem or the network self-healed,” he updated , with investigations still ongoing.

Regardless, Schwartz was keen to reassure users that no assets on the XRPL were lost as a result of the incident. “It just caused ledgers not to be seen as trusted for about an hour,” he said. “The servers knew the network wasn't working correctly and so did not report any ledgers as trusted during the incident.”

XRP is currently down 2.7% over the past 24 hours, according to The Block’s XRP Price Page . However, the asset has gained around 4% since the incident and subsequent recovery.