Release of Canton 3.5.17

Canton 3.5.17 has been released on September 10, 2026.

Summary

This is a maintenance release that brings few minor improvements and bug fixes.

Added the duration of the “output” stage to the performance metrics.
Reduced compute footprint of mempool stage.
Make speculative download during state transfer only download epochs that are below the target epoch of the state transfer.
Fix some onboarding issues with catch up.
Filter out unordered events in the mempool that exceed their max_sequencing_time.
Resolved occasional out-of-memory crashes due to unlimited buffering on the message producer side when peers were not consuming P2P messages fast enough.
P2P: fixed a re-onboarding issue that caused the newly onboarded node not to have incoming connectivity in some circumstances.
Improvements to autovacuum settings of partitions and disable manual vacuum (but allow it to be re-enabled via configuration)
Fixed an OOM caused by redundant spans being created and not closed.

gRPC flow control now defaults to automatic mode with an explicit initial window size of 1MB across all Canton gRPC connections, including CantonBFT P2P. In addition, only one among flow control window size (manual flow control) and initial flow control window size (automatic flow control) can be set at a time, otherwise a validation error is produced. This change removes the dependency on the underlying gRPC implementation’s default flow control behavior, which can vary across versions, makes it easier to troubleshoot flow control issues in the future and prevents configuration mistakes.

Mediator: Cosmetic fix for the mediator verdict sender to correctly stop retrying to send verdicts if the sequencer reports that the verdict has already been successfully aggregated.

The following Canton protocol versions are supported:

Dependency	Version
Canton protocol versions	34, 35

Canton has been tested against the following versions of its dependencies:

Dependency	Version
Java Runtime	OpenJDK 64-Bit Server VM (build 21.0.12+2-nixos, mixed mode, sharing)
Postgres	Recommended: PostgreSQL 17.10 (Debian 17.10-1.pgdg13+1) – Also tested: PostgreSQL 14.24 (Debian 14.24-1.pgdg13+2), PostgreSQL 15.19 (Debian 15.19-1.pgdg13+2), PostgreSQL 16.15 (Debian 16.15-1.pgdg13+2), PostgreSQL 18.6 (Debian 18.6-1.pgdg13+2)