On September 2, 2025, Ethereum Layer 2 solution Starknet experienced a significant mainnet outage lasting approximately three hours. This incident, attributed to a sequencer failure, marked the second major disruption within a two-month period, raising concerns about the network's reliability and scalability.

Incident Overview

The outage occurred shortly after the deployment of Starknet's Grinta upgrade (v0.14.0), which introduced a decentralized sequencer architecture utilizing the Tendermint consensus mechanism. The sequencer, responsible for ordering transactions, failed to recognize the Cairo0 code, leading to a halt in block production and transaction processing . Developers initiated a chain reorganization from block 1,960,612 to restore functionality, resulting in the loss of nearly one hour of network activity .

Previous Outages

This incident follows a 13-minute disruption on July 18, 2025, due to slow block creation and gateway delays. A more severe outage occurred in April 2024, when a rounding error bug led to a four-hour downtime. Despite these setbacks, monitoring data from QuickNode had shown nearly 100% uptime until now .

Impact on Network Metrics

Prior to the outage, Starknet had a Total Value Locked (TVL) of approximately $548 million, making it Ethereum's seventh-largest Layer 2 network . The incident led to a decline in the price of Starknet's native token, STRK, which fell more than 3% during the downtime .

Community and Developer Response

Starknet's development team promptly acknowledged the issue and worked to restore full functionality. The incident prompted discussions within the community about the robustness of the new decentralized sequencer architecture and the need for improved fault tolerance mechanisms .

The September 2025 outage highlights the challenges associated with transitioning to decentralized infrastructure in blockchain networks. While the Grinta upgrade aimed to enhance scalability and decentralization, the sequencer failure underscores the importance of rigorous testing and redundancy measures. As Starknet continues to evolve, addressing these reliability concerns will be crucial for maintaining user trust and ensuring the network's long-term success.