JMRI® is...





JMRI provides powerful tools for working with your layout:

Layout Automation

JMRI can be used to automate parts of your layout, from simply controlling a crossing gate to running trains in the background.

Supported Hardware

Donate to JMRI

JMRI Setup: Migrating System Prefixes

JMRI system names are supposed to have a specific format that starts with a "system prefix" consisting of a single letter, optionally followed by digits. Unfortunately, for a while JMRI wasn't enforcing that properly, and in a few cases JMRI set itself up with prefixes that contained multiple letters. This can cause significant long term problems, so we're getting people to migrate their configurations and panel files to the proper format.

Does this affect me?

You can check if this is an issue for your setup any of a couple ways:

How to fix the issue

To fix this issue, you update your configuration and panel files to use new prefixes.

If you encounter any problems, please ask for help on the JMRI users group. There are people there who will happily do the necessary file modifications. If your computer is connected to the Internet, you can upload your configuration as described on this page. This will make it easy for the people on jmriusers see exactly what's needed.

What happens if I don't make this change?

If you don't make this change, your existing JMRI installation will keep working fine.

If/when you update to newer versions of JMRI:

We're sorry for this inconvenience, but we really do have to fix this. Giving people over 18 months lead time seems sufficient.