v1.155.0rc1

Synapse 1.155.0rc1 (2026-06-09)

Bugfixes

• Limit the to-device EDU size to a reasonable value to mitigate long queues of to-device messages preventing outgoing federation because of the size of the transaction. (#19617)
• Work around bug that sometimes breaks joining restricted rooms that require a remote join. Contributed by @tulir @ Beeper. (#19730)
• Update Sliding Sync to return a new response immediately if a room subscription has changed and produced a new response. (#19734, #19792)
• Fix the /capabilities endpoint returning a 500 error on non-media workers when MSC4452: Preview URL capabilities API is enabled. (#19839)

Improved Documentation

• Document how to see Rust build failure output when using poetry install. (#19818)
• Document that the SQLite version included in Ubuntu LTS, aside from ESM-only versions, is included in our support policy. (#19823)

Internal Changes

• Port the Python Event classes to Rust. (#19701, #19816, #19817, #19819)
• Added tests to ensure that email notification links are sanitized. Contributed by Noah Markert. (#19741)
• Add GcpJsonFormatter logging formatter for use with Google Cloud Logging and GKE deployments. (#19775)
• Add more logging to the to-device message replication stream. (#19801, #19821)
• Port Requester class to Rust. (#19828)