Polygon Labs has warned that nodes running outdated Bor or Heimdall clients are no longer in consensus after recent hardforks, requiring urgent upgrades to maintain network compatibility and avoid operational risks
Polygon Labs has issued an urgent notice to node operators following the recent Austin and Kyoto hardforks on the Polygon PoS network, warning that any node still running pre-hardfork versions of Bor or Heimdall clients has already fallen out of canonical consensus. According to Polygon Labs, these outdated nodes are now incompatible with the main network and must be upgraded to resume normal operation and maintain network integrity.
Critical Upgrade Requirements
The Austin hardfork, which activated at mainnet block 91,949,700, introduced changes that render all Bor client versions earlier than v2.10.0 incompatible with the network. This requirement applies to all Bor node roles, including validators and full nodes. Separately, the Kyoto hardfork, which went live at block height 51,533,000 on August 18, 2024, requires Heimdall validators and full nodes to upgrade to at least v0.11.0. Polygon Labs has emphasized that nodes running older binaries past these activation points are no longer following the accepted chain history and must upgrade and resync to rejoin consensus.
Security and Performance Fixes
The Austin and Kyoto hardforks addressed several security and performance risks. Austin introduced a cap on gas consumption for Bor's processing of state-sync events from L1-to-L2 bridge deposits, closing a loophole where excessive or costly events could slow or stall block processing. It also removed the `TxDependency` extra-data field from Bor's wire format, eliminating a vector where block producers could crash peers by submitting oversized data blobs. Both changes were classified as resource-exhaustion risks by Polygon Labs.
Kyoto's most severe fix targeted a vulnerability in the handling of deeply nested `google.protobuf.Any` messages, which could have allowed a single transaction to force validators into heavy decoding workloads. The hardfork added byte-level nesting checks at both mempool and block proposal stages, and also capped fee-coin lists to prevent inefficient validation scans. Additional changes in Kyoto improved checkpoint signature normalization, made certain producer-downtime messages idempotent, and enhanced the handling of milestone votes and replay keys to prevent silent event shadowing.
Operational Impact and Guidance
Polygon Labs stated that, as of its August 27 security review, no mainnet disruptions had been observed as a result of the Austin hardfork. The company framed these upgrades as proactive measures to address potential risks before they could impact network stability. Both hardforks are binary upgrades that do not require state migration or changes to the genesis block. For node operators who missed the upgrade window and are now out of consensus, Polygon Labs recommends installing the latest compatible client, rolling back to a pre-hardfork block if necessary, and resyncing according to official guidance.
For users, developers, and service providers relying on Polygon PoS, the compatibility of node infrastructure is critical for transaction processing, data availability, and network security. Outdated nodes may experience data inconsistencies, missed transactions, or inability to participate in consensus, which can have downstream effects on applications and services built on the network.
According to public repositories, Bor v2.10.1 is the latest release as of August 28, 2024, while any version from v2.10.0 onward is compatible with the Austin hardfork. Heimdall v0.11.0 or later is required for Kyoto compatibility. Node operators are advised to verify their client versions and upgrade immediately if they have not already done so.
Polygon PoS remains one of the most widely used Ethereum scaling solutions, with a large ecosystem of DeFi, NFT, and gaming applications. As of August 2024, the network processes millions of transactions daily and supports thousands of active validators and full nodes. The timely adoption of protocol upgrades is essential to maintaining the reliability and security of the network for all participants.
For context, blockchain networks like Polygon PoS rely on a distributed set of nodes running compatible client software to maintain consensus and validate transactions. When a hardfork introduces breaking changes, any node that fails to upgrade risks falling out of sync with the rest of the network, potentially leading to data loss, missed rewards, or exposure to security vulnerabilities. Regular monitoring of upgrade announcements and prompt action are necessary for node operators to avoid operational and financial risks.
