# New Pioreactor release: 26.11.0 and 26.11.1 **URL:** \ **Category:** Software\ **Tags:** release\ **Created:** [October 14, 2026, 7:39pm UTC](https://forum.pioreactor.com/t/new-pioreactor-release-26-11-0-and-26-11-1/1254 "2026-10-14T19:39:32Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![CamDavidsonPilon](https://forum.pioreactor.com/user_avatar/forum.pioreactor.com/camdavidsonpilon/32/3_2.png) [@CamDavidsonPilon](https://forum.pioreactor.com/u/CamDavidsonPilon)\ **Post date:** [October 14, 2026, 7:39pm UTC](https://forum.pioreactor.com/t/new-pioreactor-release-26-11-0-and-26-11-1/1254/1 "2026-10-14T19:39:33Z")
👋 this is an important release for an upcoming 2.0 launch. It starts to give back some “authority” to workers (part of a longer trend to decouple leaders and workers). It also has some useful performance fixes, bug fixes, and UX improvements. [⬇ Download release\_26.11.0.zip](https://github.com/Pioreactor/pioreactor/releases/download/26.11.0/release_26.11.0.zip) ### 26.11.0 #### Breaking changes - Replaced `pio workers update-model WORKER -m NAME -v VERSION` with `pio workers model set WORKER NAME VERSION`. Added `pio workers model get WORKER` to print the worker’s model assignment as JSON. - Adding a worker now requires it to run the same software version as the leader; an older worker is rejected with a message to update it first. - Changing a Pioreactor’s model now requires the unit to be reachable and its activities to be stopped. Update workers before changing their models through the leader. - Bioreactor MQTT topics, `pioreactor///bioreactor/`, now publish `{"timestamp": ..., "value": ...}` instead of a bare number. Experiment profile expressions that read these topics need `.value`, for example `${{ ::bioreactor:current_volume_ml.value }}`. - Replaced the PWM MQTT topic `pioreactor///pwms/dc` with `pioreactor///pwms/channel_dc`, keyed by PWM channel instead of GPIO pin. Update any plugins or scripts that consume this topic. Upgrade the leader and all workers together, then reload browser tabs. #### Enhancements - Added `pio cluster leave` to remove a worker from its cluster from the worker itself, for example before moving it to another lab. It keeps the worker’s model, calibrations, estimators and `unit_config.ini`. - Adding a worker is more reliable: a failed step can be retried, a wrong SSH password fails right away, and the UI no longer gives up after 90 seconds while setup is still running. - Added automatic imports from the SD card’s boot partition. Place files in these folders on the boot partition, then reboot: - Each Pioreactor now stores its own model, so it survives reboots and is available when the leader is unreachable. Custom models defined only on a worker can now be assigned to it. New CLI commands to inspect or change the local model: - Jobs now buffer up to 10,000 MQTT messages (was 100) while the broker is unreachable, so a leader reboot or short Wi-Fi drop loses far fewer readings. - Workers now log a warning at startup if the system clock isn’t synchronised, since measurement timestamps may be wrong. - Faster data exports and chart loading, and lower browser memory use for live charts and logs during long experiments. - Added **Mount** and **Eject** buttons for USB drives on the Plugins page, with clearer guidance when a drive is missing, unmounted, or has no plugins. #### Bug fixes - Fixed `pio workers add -p ` writing the worker’s SSH password to the logs when setup failed. - Fixed commands from the leader possibly running on the wrong Pioreactor when an address is stale or reused. - Fixed dosing events being discarded when an addition would overfill the vial, which could stop dosing automations from pausing correctly. - Fixed jobs failing immediately when the leader’s web server is briefly unavailable, for example while restarting. - Automation events, bioreactor values and PWM duty cycles are now stored with the time they were produced on the worker, not the time the leader received them. - Fixed a re-added worker still pointing at its previous leader’s MQTT broker. - Fixed configuration editing being blocked when configuration history is slow or unavailable. - Fixed the Plugins page hiding plugins on read-only USB drives. - Fixed PWM duty-cycle history failing to save on a leader-only unit with no assigned model. - Fixed the monitor’s self-checks erroring when the leader is unreachable. - Fixed Akima calibration fitting with only two data points. > **[Updating the Pioreactor software | Pioreactor Docs](https://docs.pioreactor.com/user-guide/updating-software)** > > We publish new software occasionally that fixes bugs, adds new features, and improves performance. You can update your Pioreactor(s) to the latest software from the UI, or from the command line. We highly recommend keeping your Pioreactor software up... ---
**Author:** ![CamDavidsonPilon](https://forum.pioreactor.com/user_avatar/forum.pioreactor.com/camdavidsonpilon/32/3_2.png) [@CamDavidsonPilon](https://forum.pioreactor.com/u/CamDavidsonPilon)\ **Post date:** [October 20, 2026, 4:10pm UTC](https://forum.pioreactor.com/t/new-pioreactor-release-26-11-0-and-26-11-1/1254/2 "2026-10-20T16:10:18Z")
Known issues: - UI dialog boxes confirming too aggressively! hotfix incoming ---
**Author:** ![CamDavidsonPilon](https://forum.pioreactor.com/user_avatar/forum.pioreactor.com/camdavidsonpilon/32/3_2.png) [@CamDavidsonPilon](https://forum.pioreactor.com/u/CamDavidsonPilon)\ **Post date:** [October 20, 2026, 4:48pm UTC](https://forum.pioreactor.com/t/new-pioreactor-release-26-11-0-and-26-11-1/1254/3 "2026-10-20T16:48:21Z")
Fixed a bug where cancelling or dismissing some confirmation dialogs could still execute the action, including stopping activities, rebooting or shutting down Pioreactors, and deleting items. We recommend updating to 26.11.1. After updating, reload any open Pioreactor UI tabs. [⬇ Download release\_26.11.1.zip](https://github.com/Pioreactor/pioreactor/releases/download/26.11.1/release_26.11.1.zip) ### 26.11.1 #### Bug fixes - Fixed cancelling or dismissing confirmation dialogs still stopping activities, rebooting or shutting down Pioreactors, removing or unassigning workers, or deleting profiles, calibrations, estimators and camera snapshots. These actions now require explicit confirmation. Cancelling the leader system archive import also leaves the file picker closed. ---
**Author:** ![Stkral](https://forum.pioreactor.com/letter_avatar_proxy/v4/letter/s/e68b1a/32.png) [@Stkral](https://forum.pioreactor.com/u/Stkral)\ **Post date:** [October 27, 2026, 1:35pm UTC](https://forum.pioreactor.com/t/new-pioreactor-release-26-11-0-and-26-11-1/1254/4 "2026-10-27T13:35:13Z")
_ **26.11.0 update fails on armhf/Trixie workers: bundled Bookworm mosquitto packages need `libssl3`** _ I was a bit behind on updating but encountered an issue when trying to update to 26.11.0. Found a workaround with some troubleshooting and vibecoding. Maybe just a fault somewhere on my side but wanted to share either way 🙂 Below is the (Claude) summary of what I did: **Environment** - Cluster of ~30 workers plus 1 leader. All units were on 26.10.0 before updating. - Workers: armhf, Raspberry Pi OS Trixie (`libc-bin 2.41-12+rpt1`), 512 MB RAM. [model, e.g. Pi Zero 2 W / 3A+] - Leader: [model / arch] **Problem 1: mosquitto install fails (update step 7, `50_install_mosquitto.sh`)** - Mosquitto was not installed on the workers before this update. The dpkg log shows `install mosquitto → 2.0.11-1.2+deb12u2`. - The script installs the bundled `*_2.0.11-1.2+deb12u2_armhf.deb` packages. These depend on `libssl3 (>= 3.0.0)`, which doesn’t exist on Trixie (it’s `libssl3t64` there). - Result: `libmosquitto1`, `mosquitto` and `mosquitto-clients` are left unpacked but not configured, apt is left in a broken state, and the update fails on every worker. - Side effect: the Python package was already upgraded (`pioreactor-26.11.0.dist-info` is timestamped at the failed run), so `pio version` reports 26.11.0 even though steps 7 onward never ran. dpkg error: ```auto dpkg: dependency problems prevent configuration of libmosquitto1:armhf: libmosquitto1:armhf depends on libssl3 (>= 3.0.0); however: Package libssl3 is not installed. ``` **Workaround (tested on one worker, then rolled out)** bash ```auto sudo dpkg --purge mosquitto-clients mosquitto libmosquitto1 sudo apt-get update && sudo apt-get install -y libmosquitto1 mosquitto mosquitto-clients # Trixie 2.0.21-1 pio update app --version 26.11.0 ``` `50_install_mosquitto.sh` then skips the bundled packages because the installed version is ≥ 2.0. All 13 steps complete, `pio repair` reports all services active, and chrony correctly uses the leader as its time source. **Suggested fix:** detect the Debian codename and install from apt on Trixie, or bundle `deb13` packages. Can you confirm this is the intended workaround, and whether the mosquitto broker service should be enabled on workers? The Trixie package enables it by default. **Problem 2: update archives are never removed from `/tmp` on workers** - Each update attempt leaves a ~25–27 MB `/tmp/pioreactor_update_archive_*.zip` behind. After several releases and retries, about 20 had built up on the leader. - On Trixie, `/tmp` is a RAM disk (237 MB on 512 MB units). It filled up completely, and later updates failed at the copy step with `rsync: write failed ... No space left on device (28)`. - This also holds about half the RAM on these units. **Minor issues (possibly not caused by 26.11.0)** - `sudo: unable to resolve host PioXX` appears on every sudo call: the workers’ `/etc/hosts` has no entry for their own hostname. ---
**Author:** ![CamDavidsonPilon](https://forum.pioreactor.com/user_avatar/forum.pioreactor.com/camdavidsonpilon/32/3_2.png) [@CamDavidsonPilon](https://forum.pioreactor.com/u/CamDavidsonPilon)\ **Post date:** [October 27, 2026, 3:05pm UTC](https://forum.pioreactor.com/t/new-pioreactor-release-26-11-0-and-26-11-1/1254/5 "2026-10-27T15:05:45Z")
This is very helpful, thanks @Stkral ! I’ve updated the [Release 26.11.0 · Pioreactor/pioreactor · GitHub](https://github.com/Pioreactor/pioreactor/releases/tag/26.11.0) release file with some suggested fixes.