Release Notes for JMRI 5.15.4 release

Date: MM DD, 2026

From: Release Pumpkin

Subject: Test Release 5.15.4 of JMRI/DecoderPro is available for download.

This is a draft release note only; the download links do not yet work

Notes:

This is a test release. Please post a note if you encounter any new or old bugs! And please back up your JMRI files before installing this, in case you want to go back to an earlier version.

This is the next in a series of 5.15.* test releases. It requires at least Java 11 to work. We recommend that you use Java 21 if possible. (See our page on downloading Java) We expect this series to result in the next JMRI production release in July 2026. (See the tentative release schedule)

JMRI is now only available under the GNU General Public License. For more information, please see our copyright and licensing page.

Update From Older JMRI Versions

If you are currently using a version older than JMRI 5.0, please follow these instructions carefully:

1. Is your current version older than JMRI 4.12? If so, then update to JMRI 4.12 first, and ensure everything works correctly: check start-up, check things you need to be working, and check the JMRI log as well) before doing anything else. Store your configuration and panel files under a new name and use those from now on. Then continue with step 2.

   If you are currently using JMRI 4.7.3 or earlier on Linux or macOS (Windows doesn't need this), then it's very important that you update to JMRI 4.12 and carrying out the migration process described in the JMRI 4.12 release note before updating to any later release.

2. Is your current version older than JMRI 4.20? Then update to JMRI 4.20 first, and ensure that works correctly (check start-up, check things you need to be working, and check the JMRI log as well) before doing anything else. Save your preferences again. Store your configuration and panel files under a new name, use those from now on, and go on to step 3.
3. Is your current version older than JMRI 4.24? Then update to JMRI 4.24 first, and ensure that works correctly (check start-up, check things you need to be working, and check the JMRI log as well) before doing anything else. Save your preferences again. Store your configuration and panel files under a new name and use those from now on.
4. Is your current version older than JMRI 5.0? Then update to JMRI 5.0 first, and ensure that works correctly (check start-up, check things you need to be working, and check the JMRI log as well) before doing anything else. Save your preferences again. Store your configuration and panel files under a new name and use those from now on.
5. You can then install this release.

Following this multi-step order of updating via stable major releases safeguards you against possible migration issues that can arise from skipping these versions.

New problems with this release

• None yet

New warnings for this release:

• The way mouse clicks are handled has been updated. Although this has been tested with mice and trackpads, it's possible that this will cause problems with other hardware, e.g. touch panels. If you do encounter new problems with clicking on panels, please contact us on the JMRI users list.
• The RailCom handling has been updated to current standards. In particular, the enum representing the orientation has been changed from ORIENTA and ORIENTB to EAST and WEST respectively and some of the text strings have changed. These may affect any scripts you have that reference the direction of a RailCom report (tag) or parse the status messages.

Older warnings

See the JMRI 5.14 release note for more warnings predating the 5.15 development series, including pointers to various migration issues. These may be relevant to you if you're updating from an earlier version; we strongly recommend you update to at least JMRI 5.0 before installing this test release. See instructions above.

• Since JMRI 4.99.1 This test release, and all subsequent ones, require the use of Java 11 or later. We recommend that you use Java 21. Java 8 is explicitly not supported. There's more information on this migration on the JMRI Tech Road Map and JVM Capabilities pages.
• If you're using a Firefox web browser and opening JMRI help files locally (not over the web), a Firefox bug can sometimes cause it to enter a loop. There's a workaround in this JMRIusers post.
• Since JMRI 5.15.1 The serial communications library that JMRI uses has been updated. If your JMRI installation is having trouble communicating with your model railroad hardware, please contact us on the JMRI users group.

Download links:

During development leading to the actual release, you can find test download files on the continuous integration build page. These are development files, and might not be working at any particular time.

Changes since Test Release 5.15.3:

The full list of included changes is available from our GitHub code repository.

Hardware Support

Acela CTI

Anyma DMX512

Bachrus Speedo

BiDiB

CBUS

• The RailCom support has been updated:
  • DDES messages are now being decoded into RailCom tags, including the orientation, direction and motion values.
  • Receipt of a RailCom-format DDES message will now automatically create a reporter for the received device number if it doesn't already exist.
  • Related changes to the RailCom tag table have been made, see the Miscellaneous category below.

C/MRI

DCC++ and DCC-EX

DCC4pc

Direct

ESU

Hornby

Internal

IPOCSMR

JMRI Simple Server/JMRI Client

KPF-Zeller

Lenz XPressNet

LocoNet

Maple

Marklin CS2

MERG

MQTT

MRC

NCE

Oak Tree

OpenLCB / LCC

Powerline

RFID

Roco z21/Z21

Secsi

SPROG

SRCP

TAMS

TMCC

Uhlenbrock Intellibox

Zimo MXULF

ZTC

New / Updated decoder definitions

AE Model

Arnold

Bachmann

BLI

BNM Hobbies

CT Elektronik

DCC Concepts

Digikeijs (Digirails)

Digitrax

Doehler & Haas

ESU

Hattoms

Hornby

Kuehn

LaisDCC

LDH

Lenz

MD Electronics

MGP

Mistral Train Models

MTH

MRC

NCE

Norsk Modelljernbane (NJM)

Piko decoders

Public Domain and DIY decoders

QSI

Rampino Elektronic

Rautenhaus

RR-CirKits

SoundTraxx

Tam Valley Depot

TAMS

TCS

Team Digital

Technologistic (train-O-matic)

Trix Modelleisenbahn

Uhlenbrock

Umelec

Viessmann

Wangrow

ZIMO

Miscellaneous

Control Panel Editor

• Improved how clicks are handled so they'll be less finicky.

Circuit Builder

Palette

CTC Tool

DecoderPro

• Added new button and File-menu item to print the roster table as it's currently displayed, with the user's selected roster group, column setup and sort order.
• The roster entry's comment field is now available as a column in the main DecoderPro display. Multi-line comments will be displayed as multiple lines in a row with extended height. Type ctrl-return or alt-return to put a newline in the field.

  If you don't want to see this column, right-click/ctrl-click in the column heading and deselect it.

• If you have added additional columns to the Roster Table, these can now have multi-line comments.
• Decoder product ID determination has been added for PIKO decoders.

Dispatcher

• Added: physics-based acceleration
• Added: Distance based stopping (including overriding stop sensors and slowing to minimum speed within the set distance and stopping by stop sensor)

Dispatcher System

Internationalization

Layout Editor

• Provide an option to add a memory variable or a block contents field as an input text field instead of as a label. This makes it possible to change memory or block values when using the JMRI web server. Limitations:
  • If the value is not a text string, such as a roster entry, changing the displayed text will replace the item with the new text.
  • The panel zoom level must be at 1 to edit the text content.
• Improved how clicks are handled so they'll be less finicky.

NX - Entry/Exit Tool

LccPro

Logix

LogixNG

Meters and MeterFrames

OperationsPro

• New tool that allows day to name mapping. Now your Manifest or switch list can show which day or date the train departs or arrives at a location.
• New feature, the "Add Locomotives" in the "Train Build Options" allows you to select where the locomotives will terminate.
• Helper improvement, you can now specify how many helper locomotives to assign to a train. Works like the "Add locomotives" feature, except HPT is disabled.

Panel Editor

• Improved how clicks are handled so they'll be less finicky.

Permissions

Preferences

Resources

Roster

• Added: physics parameters for physics based acceleration.

Routes

Scripting

Signals

Signal Systems

• Added a color-discriminated alternate icon set to the basic-enhanced definition

Signal Heads

Signal Masts

Signal Groups

Cab Signals

Simple Signal Logic

USS CTC Logic

Switchboard Editor

Throttle

Timetable

Tracker

Turnouts, Lights, Sensors and other elements

Warrants

Web Access

Web Server

Where Used

WiThrottle Server

Virtual Sound Decoder

Z21 Server

Miscellaneous

• Some constants in the RailCom class
have been converted to Enum values. This primarily affects developers and people who've written scripts for processing RailCom information directly. In particular, the orientation values ORIENTA and ORIENTB have been changed to enum values EAST and WEST respectively.
• Additional columns have been added to the RailCom table to better show all the information that's gathered from a RailCom report.
• The macOS launchers have been updated to allow more Java versions and to have more useful error messages.

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