Polygon Heimdall V2 Mainnet Suffers 1-Hour Outage Due to Consensus Bug

The Polygon Heimdall V2 mainnet faced a temporary outage on July 27, 2025, starting at around 9:30 UTC. The disruption, attributed to a suspected “consensus bug” and the exit of an unidentified validator from the network, lasted approximately one hour [1]. Polygon confirmed that the Bor layer—responsible for block production and transaction processing—remained unaffected and continued to operate without interruption [1].

Following the restoration of the Heimdall V2 service, inconsistencies were observed in Bor node synchronization across several RPC providers. Polygon is actively working with these partners to resolve the issue. One provider has already returned to normal operation, though it is experiencing minor sync delays [1]. The network’s status was confirmed as unresponsive at the time of the outage by Polygon’s official status page [2], while QuickNode noted a network-wide stall at block height 74,592,238 [3].

This event marks a recurrence of issues previously seen with the earlier Heimdall V1 version, which caused several hours of network downtime in March 2022 due to a similar software bug [1]. The Heimdall V2 upgrade, introduced in early July 2025, aimed to enhance the network’s performance by reducing finality times to around five seconds and updating the tech stack with CometBFT and Cosmos-SDK v0.50 [1]. Despite these improvements, the complexity of the system has introduced new points of failure.

The incident underscores the ongoing challenges in maintaining consistent network uptime as blockchain systems scale and adopt more advanced technologies. As performance gains introduce technical intricacies, the balance between innovation and stability becomes a central concern for blockchain platforms like Polygon. The co-founder, Sandeep Nailwal, described the Heimdall V2 hard fork as the most technically complex in Polygon’s history since its 2020 launch [1].

While the network has resumed normal operations, the recent outage highlights the need for continued vigilance in ensuring the resilience of consensus mechanisms and infrastructure components. Polygon’s ability to quickly restore service and address synchronization issues demonstrates its capacity to manage and mitigate such disruptions. However, the incident serves as a reminder of the evolving risks in decentralized systems and the importance of robust network governance.

Sources:

[1] Cointelegraph – [https://cointelegraph.com/news/polygon-hemidall-v2-mainnet-experiences-temporary-outage](https://cointelegraph.com/news/polygon-hemidall-v2-mainnet-experiences-temporary-outage)

[2] Polygon – [https://status.polygon.technology/](https://status.polygon.technology/)

[3] QuickNode – [https://status.quicknode.com/](https://status.quicknode.com/)