Polygon PoS Nodes Must Upgrade to Avoid Falling Out of Consensus

Stale Polygon nodes lose consensus access

Polygon Labs has confirmed that any Polygon PoS node still using pre-hardfork software after the August activation dates is no longer part of the network’s agreed history. This means these nodes cannot see or process valid transactions until they upgrade and resync.

The upgrade applies to two separate clients: Bor, which handles transaction execution, and Heimdall, which manages consensus and checkpointing. Both clients received security patches intended to block potential system abuse.

Required software versions and activation blocks

Operators need to ensure they are running the correct minimum versions to remain compatible with the network.

• Bor: Version 2.10.0 or later is required after the Austin hardfork activated at mainnet block 91,949,700. The latest available release is v2.10.1.
• Heimdall: Version 0.11.0 or later is required after the Kyoto hardfork activated at mainnet block 51,533,000 on August 18 at 10:10:31 UTC.

The Austin hardfork addresses resource-exhaustion risks. It caps the gas used when processing state-sync events from L1-to-L2 bridge deposits, which previously lacked a fixed ceiling. It also removes the TxDependency extra-data field, which could otherwise allow a block producer to crash peers by submitting arbitrarily large data blobs.

The Kyoto hardfork targets Heimdall validators. It adds limits to nested protocol buffer messages to prevent expensive decoding attacks and caps fee-coin lists to stop lengthy validation scans. Other changes include normalizing checkpoint signature recovery and ensuring that repeated producer-downtime messages do not stall the network.

Node operator guidance

Polygon stated that it has not observed mainnet disruption resulting from these changes and described them as proactive fixes. Because both hardforks are binary upgrades without state migration or genesis changes, nodes that had not already diverged require no resynchronization.

For operators who have already run outdated binaries past the activation heights, Polygon recommends installing the applicable release. If necessary, nodes may need to roll back to a point before the hardfork and then resync under the guidance of the Polygon team.

Why this matters for Polygon users

While regular users interacting with decentralized apps will not experience direct disruption, node operators must act quickly. Running outdated client software now results in immediate separation from the canonical chain, meaning the node will miss new blocks and updates.

Polygon emphasizes that the disclosed changes were made to improve network stability and security rather than in response to active exploitation.

Sources

• CryptoSlate