Ronin Karst upgrade: mainnet October 7, Fusaka and L2 Contract Manager
On September 28, 2026, Ronin’s blog (opens in new tab) scheduled the Karst hard fork for Ronin mainnet on October 7, 2026 at 16:00:01 UTC. If you play on Ronin, you do not need a wallet migration or bridge step for Karst itself. RON stays the gas token, and Ronin says there will be no downtime for ordinary users.
Background
Ronin is Sky Mavis’s gaming-focused Ethereum L2 on the OP Stack. Titles such as Axie Infinity and Pixels settle activity on Ronin while players use familiar wallet flows for fees and marketplace trades.
In May 2026, Ronin completed its move to Ethereum L2, cutting emissions and routing builder pay through Proof of Distribution (opens in new tab). Karst is a scheduled execution-layer upgrade, not a new token launch or governance vote. It aligns Ronin with Ethereum’s Fusaka fork and adds tooling so core contracts can upgrade in fewer steps.
Saigon, Ronin’s public testnet, has run Karst since September 2, 2026 so builders and node operators can test before mainnet activation.
What happened
Fusaka, L2 Contract Manager, and op-contracts v7.0.0
Per the Karst upgrade post (opens in new tab):
- Karst brings Ethereum’s Fusaka hard fork to Ronin, including the latest execution-layer improvements Ronin cites for efficiency and future upgrades.
- The L2 Contract Manager lets Ronin upgrade core contracts in a single block instead of relying on Ethereum multisig transactions or client-level changes alone.
- Ronin’s L1 contracts move to op-contracts/v7.0.0, matching newer Optimism standards for bridge and rollup mechanics.
Users: no action and no downtime
Ronin repeats that no action is required for players and wallet holders. Ronin says the chain will stay usable through activation with no planned downtime for daily transactions.
Builder-facing execution changes
Most apps should keep working. Karst still changes a few limits and opcode costs builders should verify on Saigon before October 7:
| Change | Detail |
|---|---|
| Transaction gas cap | About 16.8 million gas per transaction after Karst (large multicalls, heavy batches, or big deployments may need splits) |
| Deposit exemption | Ethereum deposit transactions are exempt from the ~16.8M cap |
| Ordinary swaps | Blog example: a typical DEX swap around 10,000 gas, far below the cap |
| P256VERIFY | Roughly twice as expensive; relevant for passkeys and WebAuthn-style authentication |
| MODEXP | Higher cost plus a new 1024-byte input limit |
| bn256Pairing | Up to 300 pairs per call, down from 427 (ZK verification and BLS-style aggregation) |
| CLZ opcode | New opcode; update tooling that parses bytecode or estimates gas |
Node operator checklist
Node operators must upgrade before Karst activates. Nodes that stay on old clients stop following the chain, per Ronin.
| Step | Ronin mainnet | Saigon testnet |
|---|---|---|
| op-node Karst override | --override.karst=1791388801 | --override.karst=1788364801 |
| op-reth | Upgrade to v2.2.3 (includes an upstream bug fix) | Same requirement |
| Genesis | Download a fresh genesis.json for the network you run | Same |
| op-geth | End of support; migrate to op-reth before Karst | Same |
Ronin points operators to an updated external node setup guide and notes a recent op-reth snapshot if they need to catch up.
Who it affects
Players and collectors
Keep playing on Ronin games as usual. Karst does not ask you to sign a migration transaction, move NFTs off-chain, or bridge assets for the upgrade itself. Keep enough RON in your wallet for gas the way you already do for mints, trades, and in-game buys.
If a studio ships an unusually large on-chain batch after October 7, that is a builder-side sizing issue, not something typical daily loops should hit.
Studios and dapp builders
Test on Saigon now if your game or tool uses large multicalls, passkey login paths, MODEXP-heavy contracts, or pairing-heavy ZK flows. Register contracts for PoD the same way you did before Karst; this upgrade does not replace PoD registration (opens in new tab).
Node operators and indexers
Treat Karst like a hard deadline for client and genesis updates. Running op-geth after activation is not supported.
At a glance
| Item | Detail |
|---|---|
| Announce | September 28, 2026 (Ronin blog (opens in new tab)) |
| Mainnet activation | October 7, 2026, 16:00:01 UTC |
| Saigon Karst | Live since September 2, 2026 |
| Users | No action; no downtime stated |
| Core tech | Fusaka EL, L2 Contract Manager, op-contracts/v7.0.0 |
| Notable app deltas | ~16.8M gas cap (deposits exempt), P256VERIFY ~2×, MODEXP limits, pairing 300/call, CLZ opcode |
| Network / token | Ronin, RON |
| Platform hub | Ronin |
| Discord channel | Ronin Discord (opens in new tab) |
On Web3Raider
Closest pages:
- Blockchain hub, Ronin network, and RON
- Ronin platform hub
- Games hub for titles that settle on Ronin
- Prior coverage: L2 migration (June), Ronin Governance RGP-1
What to watch next
- Karst upgrade blog (opens in new tab) for any timing tweaks before October 7, 2026, 16:00:01 UTC.
- Saigon testing if you ship contracts that touch the gas cap or cryptographic precompiles listed above.
- Ronin docs (opens in new tab) and the node setup guide Ronin links for genesis downloads and op-reth migration steps.
- Ronin on X (opens in new tab) and the official Ronin Discord (opens in new tab) for operator support threads.
Bottom line: Finish op-reth migration, genesis updates, and Saigon tests before October 7, 2026, 16:00:01 UTC if you run Ronin nodes or ship large multicalls, passkey login, or ZK verification paths. Wallet players can keep daily Ronin loops without a Karst-specific migration step.