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Release Notes for JMRI 4.15.5 release

Date: April 19, 2019

From: Bob Jacobsen

Subject: Test Release 4.15.5 of JMRI/DecoderPro is available for download.


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 test releases. We expect this series to end in the next JMRI production release during early Summer 2019. (See the tentative release schedule)

Some of the changes involved are quite extensive. They may require a certain amount of experience before they are working well. Therefore, this test release should be considered experimental.

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 JMRI 4.11.9 or earlier, we strongly recommend that you update to JMRI 4.12 and make sure that's running OK before updating to this test release. Once you have JMRI 4.12 running OK, store your configuration and panel files and use those from then on. There have been a number of changes in serial port support, panel file format and configuration options since those earlier releases, and moving to the stable JMRI 4.12 release is a good way to work through any possible problems.

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

Known problems with this release

New warnings for this release:

Older warnings

See the JMRI 4.14 release note for more warnings predating the 4.15 development series. These may be relevant to you if you're updating from an earlier version.

Since JMRI 4.15.4 The calculation of Turnout Addresses for the Direct DCC Accessory Command ("a" command) mode has been fixed (commands are now sent to the correct accessory address rather than 4 less than the nominated hardware address). For pre-existing panels, changes will need to be made to either the actual decoder address or the panel. If help is required, ask on the jmriusers group.

Since JMRI 4.15.3 The prefix that identifies a layout connection should be a single letter, like "N" or "L", or a letter and some digits, like "K2" or "D3". Some older systems used to have longer "legacy system prefixes" like "DX", "DCCPP", "DP", "MR", "MC", "PI", and "TM". Those legacy system prefixes will now cause JMRI to issues a warning at startup. In this release, JMRI will still work with those prefixes, but they will need to be migrated to the proper form soon; JMRI 4.17.1 and later will require that this have been fixed. Therefore, this warning can't be suppressed without migrating the prefix in the connection configuration (and any associated panel files and scripts). If you're getting this warning and therefore need to do that migration, migration page.

Since JMRI 4.11.4 There are issues with the Pi-SPROG One command station operation. A number of workarounds should be applied:

Pi-SPROG One with version 2.4 or earlier firmware will cause a timeout after a track short circuit. A dialog box will open to inform the user of this. The track power will be turned off and must be turned on again using the power control.

Download links:

Please note that the download links in this and future JMRI releases link to Github servers. People are welcome to distribute the download files further via other websites, etc. If you want to check that you've received original, unmodified versions, please check the files against the checksums shown below.

Changes since Test release 4.15.4:

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

Hardware Support




New / Updated decoder definitions




Panel Editors

CTC Tool

Turnouts, Lights, Sensors and other elements


Signal Masts