The Prysm development team recently released an after-action report detailing the mainnet anomaly event that occurred after the Fusaka upgrade on December 4, 2025. The issue once threatened the stability of the Ethereum network but was ultimately mitigated thanks to the diversity mechanism of clients.
The report shows that the problem occurred at epoch 411,392 (December 4, 21:49 UTC) after the Fusaka upgrade was activated. Prysm consensus clients triggered a large amount of repeated calculations of historical states when processing specific proof data, leading to rapid exhaustion of CPU and memory resources, causing nodes to experience denial-of-service (DoS)-type performance degradation. This was not a protocol design flaw but an implementation issue within the client under certain boundary conditions.
Affected Prysm validator nodes accounted for approximately 15% to 22.71% of the network. During the event, overall validator participation rate plummeted from normally over 95% to about 75%, resulting in the network missing 41 consecutive epochs, leading to a loss of about 382 ETH in attestation rewards and approaching finality loss. Prysm core developer Terence Tsao pointed out that the computational load of replaying historical states was extremely high, and multi-threaded parallel triggering significantly slowed node performance.
It is worth noting that the Fusaka upgrade itself was successful. The upgrade introduced PeerDAS (Peer Data Availability Sampling) technology, aiming to increase Layer 2 blob capacity by eight times. The upgrade process involved no downtime or consensus forks.
The reason the Ethereum network avoided more severe consequences was due to client diversity. Besides Prysm, ten other consensus clients such as Lighthouse, Teku, and Nimbus remained functioning normally throughout the process, allowing approximately 75% to 85% of validators to stay online and ensuring the network’s finality was not compromised. If a similar issue had occurred with a higher proportion of clients, the consequences could have been more severe, including suspension of Layer 2 aggregations and validator withdrawal blocks.
After the incident, the Ethereum Foundation quickly issued emergency guidelines. The Prysm team deployed temporary runtime fixes first and released permanent solutions in versions v7.0.1 and v7.1.0. By December 5, the network participation rate had recovered to nearly 99%, and the Ethereum mainnet fully resumed normal operation within 24 hours.
Disclaimer: The information on this page may come from third parties and does not represent the views or opinions of Gate. The content displayed on this page is for reference only and does not constitute any financial, investment, or legal advice. Gate does not guarantee the accuracy or completeness of the information and shall not be liable for any losses arising from the use of this information. Virtual asset investments carry high risks and are subject to significant price volatility. You may lose all of your invested principal. Please fully understand the relevant risks and make prudent decisions based on your own financial situation and risk tolerance. For details, please refer to
Disclaimer.
Related Articles
Ethereum and XRP Price Momentum Fades While AlphaPepe Dominates As Best Crypto to Invest in April...
The ceasefire rally faded. Capital Street FX’s April 10 daily report confirmed it in numbers: Ethereum at $2,187 down 1.03%, XRP at $1.3449 down 0.87%. The momentum that the ceasefire briefly created lasted hours before the underlying conditions reasserted themselves. XRP has now posted six
BlockChainReporter1h ago
Ethereum Network Activity Claims New ATH Indicating Bullish Divergence
The Ethereum network has reached a new all-time high in activity, signaling its growing utility beyond speculation. Factors like L2 scaling and DeFi are driving this surge, suggesting strong long-term growth potential for Ethereum ($ETH).
BlockChainReporter4h ago
BlackRock withdrew 2,700 BTC and 30,000 ETH from a certain CEX.
Gate News, April 10, according to Onchain Lens monitoring, BlackRock withdrew 2,700 BTC (worth $196.87 million) and 30,000 ETH (worth $67.42 million) from a certain CEX.
GateNews7h ago
Ethereum Breaks Upward as Bullish Momentum Returns — What Next for ETH?
ETH rises above $2,200 as buyers regain control and defend key support.
Derivatives and ETF inflows show growing demand and renewed market confidence.
Critical support near $2,000 will determine if bullish momentum can continue.
Ethereum has finally shown signs
CryptoNewsLand7h ago
Tom Lee: The market is showing signs of forming a bottom; Ethereum, BMNR, and Bitcoin are recommended.
Gate News message, April 10, renowned market analyst Tom Lee posted that there are increasing signs the market bottom has already formed, even though the overall market still generally remains skeptical. Tom Lee suggested that for investors who are still skeptical, they could consider buying assets that performed ahead during the U.S.-Iran war. He pointed out that Ethereum and BMNR are among his top picks, and Bitcoin is also included among the recommendations. Tom Lee believes that crypto assets have already proven themselves to be a store of value during wartime.
GateNews8h ago
