Stacks Epoch 4.1 network upgrade

Stacks is targeting the Epoch 4.1 network upgrade for early December 2026, with the exact day not yet fixed. The upgrade concerns the Stacks network and its native coin, STX.

What is happening

Epoch 4.1 is the next network upgrade for Stacks, a Bitcoin layer 2 protocol. According to the project's Q4 priorities, it will make Clarity 7 the default version for new smart contracts on the network. Stacks lists it alongside two other fourth-quarter goals: growing Bitcoin Staking bonds and putting bonded BTC to work in ecosystem apps.

The precise activation block height has not been published. Stacks says it will announce the block height 30 days before the upgrade, so the exact timing will become clear about a month ahead of activation.

The plan was disclosed alongside the Q3 Ecosystem Report, released on October 15, 2026. The report also noted that staked STX rose from 392 million to 493 million after the PoX-5 upgrade, an increase of more than 25%, and that Bitcoin Staking has drawn 735 BTC across its first two phases. The next monthly bonding window, Bond 3, is slated to open around November 10, 2026.

Why it matters

For developers, the key change is that Clarity 7 becomes the default for new contracts. Teams building in December and later will need to plan around the updated version. The 30-day notice on the block height gives node operators, app teams and infrastructure providers time to prepare before the switch.

For STX holders and traders, the upgrade is one of several events in a busy quarter for the network, which also includes the new monthly bonding cadence and a leadership change at Stacks Labs. Network upgrades can involve operational changes, so the announcement of the activation block height is a useful checkpoint to follow. This description is informational and not financial advice.

Key details

• Date: Early December 2026 (month precision; exact day and activation block height to be announced 30 days in advance)
• Project: Stacks
• Coins: STX
• Category: Mainnet Launch
• Status: Confirmed
• Source: Crypto Briefing via TradingView