Canton 3.6.1 and Splice 0.9.0 Released, Bringing Protocol Version 36
The release redesigns how validators track commitments so memory no longer grows with the number of hosted parties, adds external calls to Daml, and removes several deprecated APIs.
Digital Asset released Canton 3.6.1 on 5 October 2026, and Splice 0.9.0, which includes the Super Validator and validator applications, was released the same day. Together they bring protocol version 36 to the Canton Network. The release notes call 3.6.1 a minor release with new features and scalability improvements.
Scalability: parties no longer weigh on memory
The largest change sits in ACS commitments, which according to the release notes were completely redesigned in protocol version 36. Validator memory use is now decoupled from the number of parties a validator hosts, and changes to hosting for non-local parties take constant time.
That matters for institutions that run one validator for many client accounts, such as custodians, exchanges and wallet providers.
New for developers
- External calls in Daml. Contracts can make deterministic calls to extension services. The feature needs Daml-LF 2.4 and protocol version 36.
- Database and security. Postgres 18 is supported, ML-DSA-65 post-quantum signatures are available as an experimental feature, and public API servers now reject TLS 1.0 and 1.1.
- Renaming. Scribe is now called Participant Query Store.
- Legacy endpoints. Ledger API endpoints deprecated in Canton 3.4 and 3.5 are disabled by default and will be removed in 3.7.
What Splice 0.9.0 changes
Splice 0.9.0 upgrades to Canton 3.6.1, which adds support for protocol version 36. The Splice notes say a Logical Synchronizer Upgrade is required to adopt the new protocol version on a network. The release also:
- removes the SV app's
/v0/dso endpoint;
- removes the Scan v0 and v1 endpoints for the active contract set and holdings;
- removes the validator's
TransferCommand, in favour of token-standard transfers;
- fixes a bug in minting delegations.
What operators should note
Release and upgrade dates for DevNet, TestNet and MainNet are set in the Canton Foundation's operations calendar, which operators were pointed to on the Canton forum on 5 October. Separately, a forum notice the same day told MainNet operators of an upgrade later that week to adopt CantonBFT ordering, with a 24-hour topology freeze from 9 am US Eastern on Friday 9 October.
Why it matters
Party scalability has been a practical limit for firms that host many accounts on a single validator, and protocol version 36 removes the link between those accounts and memory use. External calls give Daml contracts a deterministic way to use outside services. The removal of old APIs means wallets, explorers and exchanges that still rely on them need to migrate before their networks upgrade.
