How important is it to update lucee.jar?

I’ve seen people on the board recommending to update the lucee.jar file (aka “loader”?), but I’ve really got no idea what it actually does, when it’s necessary, or how important it is to keep it current.

For example, we have some installations that have been upgraded to using the webadmin update functionality, but still using lucee.jar as old as, due to the people running updates not knowing about lucee.jar. I’ve told them they “should” be updating that file but honestly, I couldn’t actually supply them with a reason.

Those installations appear to be running fine… so what’s the actual deal with lucee.jar?


OS: Windows Server 2019 / Linux / MacOS
Java Version: OpenJDK 11.x (mostly)
Tomcat Version: 9.x
Lucee Version: 5.3.x - 5.4.x

‘lucee.lco’ updates only bundle the core lucee code, but no jars.

When you do an in place upgrade via the admin, lucee downloads any missing new jars from the update provider

jars in the bundle folder with dashes instead of dots were downloaded

Whilst the loader is very lightweight, minimal and backward compatible, sometimes there are fixes/improvements in the loader

It works pretty damn well, but sometimes you might encounter an edge case, so that’s why we recommend updating the loader and or java, as people do end up running very old versions

When people have problems, we suggest updating the loader so that the lucee devs are also testing/ trying to repo against the same stack.