v3.1

---

Key Information	Details
Version	Conflux v3.1.0
Hardfork Introduced	Yes
Incompatible Changes	Yes (CIP-166, CIP-167, CIP-172, CIP-173, CIP-174, CIP-175, CIP-176)

Introduction

Conflux v3.1.0 is a hardfork introducing EVM compatibility changes from Ethereum's Osaka upgrade, bug fixes, a security update (details disclosed after activation), and RPC changes.

Upgrade Overview

• EVM compatibility:
  • The CLZ opcode for counting leading zeros is introduced (CIP-166).
  • A precompile for secp256r1 (P-256) signature verification is introduced, the curve widely used by WebAuthn and passkeys (CIP-167).
  • The ModExp precompile gets an upper bound on input length and repriced gas (CIP-174).
• Bug fixes:
  • Every transaction in a block must use canonical RLP encoding, fixing the issue where the same transaction could correspond to more than one hash (CIP-172).
  • PoS dispute evidence verification defects are fixed, and the CIP-156 stake lock is extended to validators whose stake is already entirely unlocking (CIP-173).
  • Cross-space calls now resolve EIP-7702 delegation, matching calls made within eSpace (CIP-175).
  • Access list entries for the same address all warm their storage keys, instead of only the last entry (CIP-176).
• Security update: this upgrade includes a fix for a security issue. To prevent exploitation, the related source code and details will be published after the network upgrade is complete.
• RPC changes:
  • New RPCs: eSpace eth_createAccessList and eSpace parity style trace_call.
  • The Core space RPC service has been migrated to the jsonrpsee framework.
  • The TCP JSON-RPC server has been removed, along with the jsonrpc_tcp_port and jsonrpc_local_tcp_port options. The HTTP and WebSocket endpoints are unchanged.
  • The WebSocket endpoint now applies the jsonrpc_cors setting, which previously affected HTTP only.
  • Request throttling is enforced on the jsonrpsee stack and now also covers batch requests.
  • The light node supports the pub/sub namespace.
  • Fixed 4byteTracer dropping calls with no arguments (bare function selector).
  • Fixed phantom transaction trace recovery for blocks before CIP-90 activation.
  • eSpace log filters reject a topics array with more than four positions.
  • EIP-7702 authorization objects reject a yParity greater than 1.
  • cfx_sendTransaction and cfx_signTransaction return an error when from is omitted.
  • The PoS tx_by_version RPC returns null for version 0.

Upgrade Notes

1. Replace pos_config/pos_config.yaml with the copy shipped in this release. The file is parsed strictly and an old copy will not load, so the node will not start. If you changed paths such as base.data_dir, storage.dir or logger.file, carry them over — those keys are unchanged. pos_config/genesis_file is no longer used and can be deleted.
2. The first start after upgrading will take considerably longer than a normal restart. The shipped run/testnet.toml now sets use_isolated_db_for_mpt_table = true, and the node rebuilds the latest MPT snapshot once to make that switch. Later restarts are unaffected.

CIP List

CIP-166

CIP-166 Add CLZ Opcode replicates EIP-7939, adding the CLZ opcode for counting leading zeros.

CIP-167

CIP-167 Precompile for secp256r1 Signature Verification replicates EIP-7951, introducing a precompile for signature verification on the secp256r1 (P-256) curve, which is widely used by WebAuthn, passkeys and similar schemes.

CIP-172

CIP-172 Enforce Canonical RLP Encoding for Transactions requires every transaction in a block to use canonical RLP encoding, fixing an issue where the same transaction could correspond to more than one hash. Nodes also reject these transactions from the transaction pool immediately upon upgrade, without waiting for activation.

CIP-173

CIP-173 Fix PoS Dispute Evidence Verification fixes defects in the verification of PoS dispute evidence, and extends the CIP-156 stake lock to a validator whose stake is already entirely unlocking.

CIP-174

CIP-174 Bound ModExp Precompile Input Length replicates EIP-7823 and EIP-7883, setting an upper bound on the input lengths of the ModExp precompile and raising its gas pricing.

CIP-175

CIP-175 Resolve EIP-7702 Delegation in Cross-Space Calls fixes cross-space calls not resolving an EIP-7702 delegation, bringing the behavior in line with calls made within eSpace.

CIP-176

CIP-176 Fix Access List Storage Key Warming fixes the case where, when the same address appears in several entries of an access list, only the storage keys of the last entry were warmed.

Releases

Testnet

Key Information	Details
Release	Conflux v3.1.0-testnet
Announcement	Conflux v3.1.0-testnet Hardfork Upgrade Announcement (August 3, 2026)
Deadlines	Node Upgrade: Before epoch number reaches 259240000 (estimated on August 7th 2026) CIP-173 Activation: When PoS block number reaches 3870720 (estimated on August 8th 2026)

The mainnet release will be published after the testnet upgrade completes.