Stacks 4.0 Hard Fork Targets July 29 as Exchanges Halt STX Transfers

Stacks 4.0.1 Sets a Bitcoin-Block Activation Trigger

The target is an estimate because the fork is tied to Bitcoin block 960,230, not a clock controlled by Stacks. The Foundation lists the expected date as Wednesday, July 29, and asks operators to run stacks-core 4.0.1 before the block arrives.

Clarity 6 is the next version of Stacks’ smart-contract language. Bitcoin Stacking, described by the project as part of the new epoch, is the other central change. The Foundation says the community vote cleared the approval threshold, while the official release describes the hard fork as mandatory.

The economic change is narrower than a new supply schedule. The Foundation says major supply mechanics remain unchanged but the block reward will reset to a baseline 1,000 STX after having operated at a different level since April. That does not establish a price effect, but it makes the activation relevant to operators and participants tracking protocol issuance.

Stacks has been preparing the adjacent Bitcoin Staking system in parallel. Its Q2 ecosystem report said the PoX-5 mechanism had reached public testnet and was in audit ahead of a Q3 mainnet launch. That work is separate from simply running the 4.0.1 client, but both developments are aimed at building Bitcoin-native finance on the network.

Bithumb Plans a Temporary STX Transfer Pause

Exchange customers may see a different operational effect from the protocol’s own statement. The Foundation says the upgrade does not change STX deposit or withdrawal logic, but an exchange still has to update and validate its own nodes.

Bithumb said in a July 24 notice that it will suspend STX deposits and withdrawals from 09:00 KST on July 29 for the network upgrade and node-server maintenance. The exchange said trading would continue during the suspension and transfers would resume once network stability is secured; it did not provide a reopening time.

That distinction is important for holders moving assets between venues or into self-custody. A temporary exchange pause does not mean the protocol has stopped processing transfers, but deposits sent close to a cutoff can face confirmation or account-credit delays under the venue’s procedures.

The event also comes after a turbulent period for Bitcoin-linked execution layers. Botanix’s planned shutdown and withdrawal window showed how user access can become the immediate issue when a Bitcoin DeFi network changes course. Stacks is preparing a scheduled consensus upgrade, not a wind-down, but users face the same practical need to distinguish a network event from an exchange’s service timetable.

Operators Face the Real Consensus Deadline

The Foundation says an operator running the Stacks Blockchain API also needs the corresponding v9 release. It says the major API version requires an Event Replay; an operator who skips that process would need to wipe the API’s chainstate and Postgres database before resynchronizing.

That makes this more than a wallet-facing software update. Nodes, signers, API operators and custodians must coordinate around the same Bitcoin height, while exchanges need to reconcile deposits and withdrawals against the post-fork network. The most consequential test is whether that transition occurs without a prolonged split in service or reconciliation delays.

Stacks’ broader pitch is to put Bitcoin balances into programmable markets while retaining a Bitcoin connection. Large U.S. banks’ exploration of bitcoin products is a different institutional route, but it underscores the competition to define how Bitcoin exposure is held, settled and used rather than merely bought.

The wider market remained cautious. The Crypto Fear and Greed Index read 26, in the Fear range, on July 26, compared with 27 the day before and 28 a week earlier.

The next checkpoints are the approach to Bitcoin block 960,230, confirmations from major custodians and exchanges that their infrastructure is ready, and evidence that updated nodes stay on a single chain. The timing remains an estimate, and neither the Foundation nor Bithumb has disclosed a universal post-upgrade transfer-resumption schedule.