On July 30, 2025, Polygon's Heimdall consensus layer experienced a temporary one-hour outage triggered by an unexpected validator exit that revealed a critical bug in the newly upgraded Heimdall V2 infrastructure. The disruption occurred between 09:30 UTC and 11:01 UTC, pausing block finalization while Polygon's Bor execution layer continued processing transactions uninterrupted.
The incident stemmed from a coordination flaw in Heimdall V2 – recently upgraded to CometBFT and Cosmos SDK v0.50 to achieve five-second finality times – which surfaced during the validator exit sequence. Although Bor maintained transaction sequencing, services relying on finalized states (block explorers, DeFi applications) experienced disruptions due to RPC desynchronization. Polygon Labs deployed an emergency patch within the hour, confirming no funds were compromised and emphasizing network resilience.
Polygon's native token POL dipped 2.5-3% during the outage but stabilized rapidly post-resolution. This marks the network's second Heimdall-related incident in 2024, following a similar March event. In response, Polygon Labs committed to enhanced validator transition protocols and improved infrastructure provider coordination, framing the event as a stress test that will inform ongoing Polygon 2.0 development.
