Catenaa, November 24, 2025- Cardano’s blockchain split into two on Nov. 21 after a crafted delegation transaction triggered a software flaw first reported in 2022, causing exchanges to pause ADA activity while developers rushed to contain the disruption.
The event began when the malformed transaction passed new node checks but was rejected by older systems, creating mismatched ledger states across the network.
A developer later said they performed the test without proper safeguards, which raised questions about intent and preparation. Cardano teams deployed emergency patches within three hours. The network reached natural consensus the next day as blocks realigned.
During the split, block explorers showed inconsistent data. Some DeFi applications processed actions on one chain while related transactions settled on the other.
Exchanges, including Coinbase and Upbit, temporarily halted deposits and withdrawals as they monitored chain stability. Confirmation times slowed.
Some failed as nodes attempted to reconcile the forked history. Cardano’s core organizations coordinated the response while advising operators to update systems and review node versions.
The situation escalated when founder Charles Hoskinson said the incident resembled a planned attack. He said federal investigators began assessing the event soon after the developer acknowledged responsibility on social media.
A fact sheet from Intersect stated that law enforcement agencies were notified because the transaction was intentionally designed to trigger the flaw.
The announcement prompted an IOG engineer to resign. They expressed concern that routine development errors could now carry legal risks. ADA’s price fell as much as 16 percent before recovering part of the loss.
