# Upcomming RMW Feature Freeze - April 6th, 2026 - ROS Lyrical

**URL:** <https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696>\
**Category:** ROS General\
**Tags:** release, ros2, rmw, lyrical\
**Created:** [March 31, 2026, 3:29pm UTC](https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696 "2026-03-31T15:29:08Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![sloretz](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.openrobotics.org/sloretz/32/23113_2.png) [@sloretz](https://discourse.openrobotics.org/u/sloretz)\
**Post date:** [March 31, 2026, 3:29pm UTC](https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696/1 "2026-03-31T15:29:08Z")

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Hi all,

On 2026-04-07T06:59:00Z, we will freeze all RMW-related packages to prepare for the upcoming `Lyrical Luth` release on 2026-05-22T07:00:00Z.

Once this freeze takes effect, we will not accept new features to the RMW packages until Lyrical branches from ROS Rolling. This restriction applies to the following packages and vendor packages:

- [rmw\_fastrtps](https://github.com/ros2/rmw_fastrtps.git)
- [rmw\_cyclonedds](https://github.com/ros2/rmw_cyclonedds.git)
- [rmw\_connextdds](https://github.com/ros2/rmw_connextdds.git)
- [rmw\_zenoh](https://github.com/ros2/rmw_zenoh)
- [Fast-DDS](https://github.com/eProsima/Fast-DDS)
- [Fast-CDR](https://github.com/eProsima/Fast-CDR)
- [cyclonedds](https://github.com/eclipse-cyclonedds/cyclonedds)
- [iceoryx](https://github.com/eclipse/iceoryx)
- [zenoh\_cpp](https://github.com/eclipse-zenoh/zenoh-cpp)

We still welcome bug fixes after the freeze date.

Find more information on the Lyrical Luth release timeline here: [ROS 2 Lyrical Luth (codename ‘lyrical’; May, 2026)](https://docs.ros.org/en/rolling/Releases/Release-Lyrical-Luth.html#release-timeline).

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**Author:** ![sloretz](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.openrobotics.org/sloretz/32/23113_2.png) [@sloretz](https://discourse.openrobotics.org/u/sloretz)\
**Post date:** [April 6, 2026, 3:49pm UTC](https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696/2 "2026-04-06T15:49:45Z")

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Friendly reminder that the ROS Lyrical RMW freeze is today, about 15 hours from now.

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**Author:** ![sloretz](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.openrobotics.org/sloretz/32/23113_2.png) [@sloretz](https://discourse.openrobotics.org/u/sloretz)\
**Post date:** [April 7, 2026, 7:00am UTC](https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696/3 "2026-04-07T07:00:24Z")

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The ROS Lyrical release has now reached RMW Feature freeze. However, there are significant issues with all 4 of ROS Lyrical’s Tier 1 RMW implementations. I will raise these issues in the ROS PMC meeting to decide what to do about them.

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**Author:** ![sloretz](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.openrobotics.org/sloretz/32/23113_2.png) [@sloretz](https://discourse.openrobotics.org/u/sloretz)\
**Post date:** [April 8, 2026, 12:37am UTC](https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696/4 "2026-04-08T00:37:50Z")

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The ROS Lyrical RMW freeze is delayed by 1 week: [Delaying Lyrical RMW and Feature Freezes](https://discourse.openrobotics.org/t/delaying-lyrical-rmw-and-feature-freezes/53858)

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**Author:** ![christian](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.openrobotics.org/christian/32/14876_2.png) [@christian](https://discourse.openrobotics.org/u/christian)\
**Post date:** [April 11, 2026, 10:20am UTC](https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696/5 "2026-04-11T10:20:04Z")

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Is the information at [Lyrical Luth (codename ‘lyrical’; May, 2026) — ROS 2 Documentation: Rolling documentation](https://docs.ros.org/en/rolling/Releases/Release-Lyrical-Luth.html#middleware-implementation-support) up to date? It currently states:

> The default middleware in ROS Lyrical is **rmw\_fastrtps\_cpp**.

Is this true? I was under the impression that the next LTS release would use `rmw_zenoh_cpp` and I was looking very much forward to having a better “out of the box” performance with the Zenoh RMW. I cannot find reliable sources claiming that Zenoh will be the default, so maybe this was just wishful thinking and the only goal was to make it “Tier 1”.

Are there such efforts to eventually make `rmw_zenoh_cpp` the default RMW in ROS 2?

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**Author:** ![mjcarroll](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.openrobotics.org/mjcarroll/32/35469_2.png) [@mjcarroll](https://discourse.openrobotics.org/u/mjcarroll)\
**Post date:** [May 6, 2026, 7:26pm UTC](https://discourse.openrobotics.org/t/upcomming-rmw-feature-freeze-april-6th-2026-ros-lyrical/53696/6 "2026-05-06T19:26:40Z")

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Correct, the default middleware for Lyrical is `rmw_fasrtps_cpp`.

The goal for the `kilted` release was to bring Zenoh to “Tier 1”. Changing the default middleware was not considered by the PMC for this release cycle. It could potentially be done in future release cycles.