Bitcoin Cash Upgrade 2026

The May 2026 upgrade is now active on Chipnet – Bitcoin Cash's 6-month-early preview network – at block 279,792! 🎉

This upgrade completes the restoration of Bitcoin Script on Bitcoin Cash (CashVM), making CashVM a simple, ultra-efficient, high-level programming environment for sound money.

Over the last decade, Bitcoin Cash has delivered:

• 2018: Opcode restoration (OP_CAT, OP_XOR, OP_DIV, OP_MOD, etc.) and data signatures,
• 2019: Schnorr signatures with batch verification,
• 2020: Density-based signature limits,
• 2022: OP_MUL and introspection,
• 2023: Cross-covenant commitments (CashTokens),
• 2025: Density-based general limits and bigints,
• 2026: Loops, functions, bitwise, and Pay-2-Script.

Each upgrade carefully preserved Bitcoin Cash's transaction-level parallelization, enabling global-scale, layer-1 throughput – without compromising Bitcoin Cash's scalability, decentralization, and censorship-resistance.

Fully-validating, archival BCH nodes run on consumer hardware and still outperform clusters of high-powered, centralized sequencers required by account-based networks.

With this upgrade, CashVM becomes even more powerful, allowing contract developers to efficiently implement post-quantum cryptography, homomorphic encryption, zero-knowledge proof systems, and more – without waiting for network upgrades.

Case Study: Quantumroot

Quantumroot is a quantum-secure vault contract design offering full 256-bit classical, 128-bit quantum security strength. Possible since May 2025, but made 10-100× more efficient by the 2026 upgrade: Quantumroot sweep transactions are 15% smaller per-UTXO than P2PKH wallets.

Upgrade Details

The 2026 upgrade includes four Bitcoin Cash Improvement Proposals (CHIPs):

Loops CHIP

Introduces the well-established, OP_BEGIN/OP_UNTIL loop construction to CashVM, bounded by the density-based limits activated in the 2025 upgrade. Loops eliminate duplication in repeated procedures, significantly reducing transaction sizes and enabling previously impractical constructions.

Functions CHIP

Enables factoring of contract bytecode into reusable functions with OP_DEFINE/OP_INVOKE, eliminating duplicated logic and reducing transaction sizes. Functions improve the efficiency of complex financial and cryptographic computations, including zero-knowledge proof verification, homomorphic encryption, post-quantum cryptography, and more.

Bitwise CHIP

Re-enables bitwise operations, including OP_INVERT for bit inversion, arithmetic shifts (OP_LSHIFTNUM and OP_RSHIFTNUM) for numeric values, and binary/logical shifts (OP_LSHIFTBIN and OP_RSHIFTBIN) for binary data. These operations allow CashVM contracts to more efficiently implement a variety of financial and cryptographic algorithms.

Pay-2-Script CHIP

Makes Pay-2-Script (P2S) outputs standard, enables longer token commitments (up to 128 bytes), and unifies the standard unlocking bytecode length limit with the consensus limit (10,000 bytes). These changes improve wallet ecosystem safety, simplify contract design, and reduce transaction sizes for many vault, multi-party covenant, and decentralized financial applications.Technical Specs

For more details, see the CHIPs:

• Loops CHIP
• Functions CHIP
• Bitwise CHIP
• Pay-2-Script CHIP