Harmony is shutting down its own blockchain. On 6 September 2026 its team said "it is time to fully sunset the Harmony network" and proposed moving the ONE token to Ethereum. Under the plan, the final balances are snapshotted and matching ERC-20 tokens go to the same wallet addresses, so holders don't need to claim anything. Validators could stop their nodes from 10 September 2026. Harmony has also said it will close its official block explorer on 18 November 2026. The plan came weeks after an exploit in August 2026 created more than three trillion unauthorised ONE.
What happened, in order
11–12 August 2026: unauthorised ONE minted
- CoinDesk first reported on 12 August that about 4 billion new ONE had been created, roughly a 26% rise on the ~15 billion supply. ONE fell about 40% during Asian morning hours.
- That day Harmony confirmed the attack. It told node operators to install an emergency update, paused its token bridge and asked exchanges to freeze funds linked to four wallet addresses.
- Harmony's later reconstruction, as reported by The Block and CoinDesk in September, put the total at more than three trillion unauthorised ONE across six transactions.
- On cause, The Block cites Harmony on two problems:
- a flaw in cross-shard receipt verification that let valid receipts be processed more than once - a bug in the quorum check.
- Security firm Halborn wrote on 24 August that the consensus code checked quorum by counting public keys in a signature mask, not the validators that actually signed. Because public keys are public, empty blocks could mint tokens without real consensus.
Rollback
Harmony rolled the chain back to a point before the forged tokens appeared. According to CoinDesk (7 September 2026), the rollback permanently removed more than 109,000 transactions.
6 September 2026: the shutdown proposal
Harmony announced the plan on X. CoinDesk and The Block reported these terms:
- Status: "explicitly non-binding", with a disclaimer that "all plans are subject to change". Harmony has not said whether the plan will go through its governance process.
- Reason given: threats from state actors and AI agents.
- Validators: they could start shutting down nodes from 7 a.m. Pacific on 10 September 2026. Harmony set aside $1.372 million, equal to validator rewards in the year before the exploit. The money goes to validators who shut down on time, sign an agreement, keep their stake and take "governor" roles in the new project.
- Snapshot: taken at the final block. It covers user wallets, staking delegations, validator rewards, smart contracts and centralised exchanges.
- New token: ERC-20 ONE on Ethereum, sent to the same addresses. Total supply and emission rate stay the same. Delegated stakes and unclaimed rewards go to individual governor vaults.
- Review: Harmony said it would publish the contract, the snapshot calculations and the airdrop scripts.
- New direction: validator rewards are redirected to what Harmony calls a "Remix Economy for AI Video". AI video creators publish open prompts and assets, fans remix them, and AI agents produce more clips from each remix.
What cannot migrate
Multisig safes, liquidity pools and on-chain apps cannot be carried over. Harmony told users to exit all smart contracts before 10 September 2026. Any position still held in a contract on the old chain is not covered by the automatic airdrop.
18 November 2026: explorer closes
TokenPost reported on 21 October 2026 that Harmony will close explorer.harmony.one on 18 November 2026. Explorer data from before 2025 must be exported by then. A planned lookup tool at migrate.country will cover address activity and transactions from 1 January 2025 onward, but not earlier records.
What Harmony was
- Design: Harmony launched in 2019 as a sharded proof-of-stake Layer 1 that runs Ethereum applications. Its documentation gives 2-second transaction finality and describes four mainnet shards.
- Consensus: Effective Proof-of-Stake (EPoS). To limit stake concentration, each validator key's stake is capped between 85% and 115% of the median stake. Consensus needs more than two-thirds of committee voting power.
- Block reward: each confirmed block paid 7 ONE to the validators that signed it.
- Founder: Stephen Tse.
Where does your ONE end up after the move to Ethereum?
Answer where your ONE sat on the Harmony chain to see what the shutdown plan says happens to it.
Where was your ONE held on the Harmony chain?
- In a wallet I control → Same address, no claim needed
- Delegated to a validator for staking → Stake goes to a governor vault
- On a centralised exchange → Covered by the snapshot
- In a multisig safe, liquidity pool or on-chain app → next question
Did you exit that smart contract before 10 September 2026, as Harmony told users to?
- Yes, the ONE went back to my own wallet → Same address, no claim needed
- No, it is still in the contract → Not covered by the automatic airdrop
Under the plan, final balances are snapshotted and matching ERC-20 ONE is sent to the same address on Ethereum. Check the Ethereum address that matches your Harmony wallet. The plan says no claim is needed, so treat any 'claim' site as a likely impersonation.
The snapshot covers staking delegations and validator rewards. Under the plan, delegated stakes and unclaimed rewards go to individual governor vaults on Ethereum.
Centralised exchanges are one of the five categories in the final-block snapshot. The article does not say how each exchange will credit its users, so watch for that exchange's own notice.
Multisig safes, liquidity pools and on-chain apps cannot be carried over. A position still held in a contract on the old chain is outside the automatic migration. Look for Harmony's official guidance before assuming it will be credited.
This follows Harmony's non-binding 6 September 2026 plan, which may still change; it cannot check your balance, confirm the airdrop has happened, or recover explorer records from before 2025.
The earlier security record
- June 2022: Harmony's Horizon cross-chain bridge lost about $100 million (Elliptic's figure: $99.7 million).
- January 2023: the FBI attributed the theft to North Korea's Lazarus Group and APT38.
- Late 2023: CoinDesk reported a staking bug that created about 146.3 million ONE.
Together with the 2026 exploit, this record is the background to Harmony's stated reason for giving up an independent chain.
Earlier history
In September 2021 Harmony announced an ecosystem fund of more than $300 million in ONE, to be paid out over four years. CoinDesk and The Defiant reported it at the time.
What ONE holders should check
- Check the Ethereum address that matches your Harmony wallet for the ERC-20 ONE balance. The plan sends tokens to the same address.
- Funds that were in multisigs, liquidity pools or apps on the Harmony chain are outside the automatic migration. Look for Harmony's official guidance before assuming they will be credited.
- Export any pre-2025 explorer records you need before 18 November 2026.
- Expect impersonation and fake "claim" sites during migrations. The plan says no claim is needed.
Harmony has called the plan non-binding, so the migration terms above may still change.
