0xPolygon/bor - v2.9.1 New

Published: Jul 28, 2026

Release Summary

Bor v2.9.1 is a significant release featuring two major upgrades enabled by default: BlockSTM v2 for parallel transaction execution and devp2p peer jailing for enhanced network resilience. This version also delivers crucial reliability fixes, expanded RPC capabilities for tracing and fee data, and numerous stability improvements.

Major Features

BlockSTM v2 Parallel Execution: This release introduces a completely redesigned parallel transaction execution engine, BlockSTM v2. It speculatively executes transactions in a block concurrently, validates their reads, and re-executes only those that become stale. This new engine, enabled by default, provides a significant performance boost, delivering approximately 1.6x more throughput than serial execution in benchmark tests (570 Mgas/s vs. 350 Mgas/s). Several follow-up fixes have been included to correct divergences from serial execution, hardening the engine against potential bad blocks and ensuring state root consistency.

Devp2p Peer Jailing: To improve network stability and reduce unnecessary peer churn, the simple peer-drop mechanism has been replaced with a sophisticated "peer jailing" system. Instead of immediately dropping peers for transient issues like timeouts, the new system applies a graded response:
- Transient failures result in a short-term soft backoff.
- Repeated soft failures within a window escalate to a temporary local jail.
- Persistent issues, like serving invalid chains or repeated whitelist mismatches, lead to a drop and a temporary ban, preventing immediate reconnection.
This makes nodes more resilient to minor network fluctuations while still protecting against genuinely malicious or faulty peers.

New RPC and Tracing Capabilities

Parity-Compatible Tracing: An OpenEthereum/Parity-compatible trace_* RPC namespace has been added. This is a major feature for archive node operators, indexers, and analytics tools. It is opt-in and can be enabled with the --rpc.enabletrace flag on archive nodes. Implemented methods include trace_block, trace_transaction, and trace_callMany.

New RPC Methods: The release adds two other useful RPC methods:
- eth_baseFee: Returns the base fee for the next block.
- debug_traceCallMany: Allows tracing multiple calls in a single bundled RPC request.

Reliability and Performance Fixes

Miner Stall Recovery: A fix has been implemented to recover the block producer from a permanent stall that could occur when a block build process became wedged, ensuring block production continues reliably.

Freezer Read-Lock Contention: A performance bottleneck where header lookups could block during a freezer cycle has been resolved. This fix prevents RPC timeouts and improves performance, especially for validators proposing milestones.

Observability and Stability:
- New p2p observability metrics have been added, including a peer drop counter (p2p/peers/drops) and ping latency timer (p2p/peers/ping/latency), giving operators better insight into network health.
- A series of fixes for race conditions have been merged, improving the stability of the transaction pool, miner, and downloader.
- RPC endpoints for log filtering now correctly honor context cancellation, preventing server resources from being held by disconnected clients.

Release Notes

Bor v2.9.1 introduces two major features enabled by default: BlockSTM v2 for parallel transaction execution and devp2p peer jailing for improved network resilience. The release also includes miner reliability fixes, new tracing and fee RPC capabilities, observability improvements, and race-condition fixes across transaction processing and state execution.

## What's Changed

- feat: add p2p observability metrics by [@vbhattaccmu](https://github.com/vbhattaccmu) in [#2242](https://github.com/0xPolygon/bor/pull/2242)
- core, blockstm, state: add BlockSTM v2 parallel transaction execution by [@cffls](https://github.com/cffls) in [#2210](https://github.com/0xPolygon/bor/pull/2210)
- CI/CD consolidation on Bor by [@sanketsaagar](https://github.com/sanketsaagar) in [#2249](https://github.com/0xPolygon/bor/pull/2249)
- chore: update go.mod by [@kamuikatsurgi](https://github.com/kamuikatsurgi) in [#2254](https://github.com/0xPolygon/bor/pull/2254)
- chore(deps): bump CometBFT fork pin to v0.3.8-polygon by [@pratikspatil024](https://github.com/pratikspatil024) in [#2263](https://github.com/0xPolygon/bor/pull/2263)
- ci-cd improvements by [@vbhattaccmu](https://github.com/vbhattaccmu) in [#2262](https://github.com/0xPolygon/bor/pull/2262)
- core/state, core: fix BlockSTM v2 vs serial divergences behind recent bad blocks by [@cffls](https://github.com/cffls) in [#2270](https://github.com/0xPolygon/bor/pull/2270)
- core/forkid: add Amoy and mainnet fork ID test cases by [@manav2401](https://github.com/manav2401) in [#2271](https://github.com/0xPolygon/bor/pull/2271)
- fix: pin kurtosis-pos to v1.3.4 by [@kamuikatsurgi](https://github.com/kamuikatsurgi) in [#2273](https://github.com/0xPolygon/bor/pull/2273)
- fix nightly race test flakes by [@pratikspatil024](https://github.com/pratikspatil024) in [#2278](https://github.com/0xPolygon/bor/pull/2278)
- fix new transaction flow race test by [@pratikspatil024](https://github.com/pratikspatil024) in [#2282](https://github.com/0xPolygon/bor/pull/2282)
- feat: add devp2p peer jailing by [@vbhattaccmu](https://github.com/vbhattaccmu) in [#2283](https://github.com/0xPolygon/bor/pull/2283)
- miner: recover Veblop producer stall when a build wedges with no pending task by [@lucca30](https://github.com/lucca30) in [#2287](https://github.com/0xPolygon/bor/pull/2287)
- stabilize skeleton timeout requeue test by [@pratikspatil024](https://github.com/pratikspatil024) in [#2291](https://github.com/0xPolygon/bor/pull/2291)
- ethapi, eth: implement `eth_baseFee` RPC method by [@wjmelements](https://github.com/wjmelements) in [#2231](https://github.com/0xPolygon/bor/pull/2231)
- backport from master to develop by [@lucca30](https://github.com/lucca30) in [#2274](https://github.com/0xPolygon/bor/pull/2274)
- core/state, core: add exact-writer validation for v2 destruction-resolved reads by [@cffls](https://github.com/cffls) in [#2290](https://github.com/0xPolygon/bor/pull/2290)
- backport v2.9.0 by [@kamuikatsurgi](https://github.com/kamuikatsurgi) in [#2296](https://github.com/0xPolygon/bor/pull/2296)
- core/rawdb: avoid the freezer read lock for recent header lookups by [@marcello33](https://github.com/marcello33) in [#2288](https://github.com/0xPolygon/bor/pull/2288)
- chore: remove SonarQube/SonarCloud integration by [@0xCVH](https://github.com/0xCVH) in [#2298](https://github.com/0xPolygon/bor/pull/2298)
- build(deps): bump `golang.org/x/crypto` from 0.51.0 to 0.52.0 by [@dependabot](https://github.com/dependabot) in [#2299](https://github.com/0xPolygon/bor/pull/2299)
- miner: stabilize freed gas feedback test by [@pratikspatil024](https://github.com/pratikspatil024) in [#2300](https://github.com/0xPolygon/bor/pull/2300)
- eth/filters: honor context cancellation in Bor block-log range scans by [@lucca30](https://github.com/lucca30) in [#2259](https://github.com/0xPolygon/bor/pull/2259)
- feat: implement `debug_traceCallMany` by [@manav2401](https://github.com/manav2401) in [#2257](https://github.com/0xPolygon/bor/pull/2257)
- txpool/legacypool: fix fillPool TOCTOU and remove debug prints by [@lucca30](https://github.com/lucca30) in [#2269](https://github.com/0xPolygon/bor/pull/2269)
- agents: fetch team standards from `0xPolygon/pos-standards` by [@marcello33](https://github.com/marcello33) in [#2304](https://github.com/0xPolygon/bor/pull/2304)
- enable trace methods by [@tmeinlschmidt](https://github.com/tmeinlschmidt) in [#2294](https://github.com/0xPolygon/bor/pull/2294)

## New Contributors

- [@0xCVH](https://github.com/0xCVH) made their first contribution in [#2298](https://github.com/0xPolygon/bor/pull/2298)
- [@tmeinlschmidt](https://github.com/tmeinlschmidt) made their first contribution in [#2294](https://github.com/0xPolygon/bor/pull/2294)

**Full Changelog:** [v2.9.0...v2.9.1](https://github.com/0xPolygon/bor/compare/v2.9.0...v2.9.1)

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