This is a test release for some changes necessary to support WebUI3. This version of FluidNC is supposed to work with either the existing WebUI version 2 or the new WebUI version 3. To test WebUI3 you can get the index.html.gz from https://github.com/bdring/FluidNC/blob/WebUI3/FluidNC/data3/index.html.gz .
If you use WebUI3 and then go back to WebUI2, WebUI2 might not start correctly. If you have this problem, you can fix it by deleting the preferences.json file with $localfs/delete=preferences.json . The problem is caused by WebUI3 creating a new preferences.json that is in a format that WebUI2 does not understand.