Note. Like with editing the registry, in this case you also need to proceed with maximum care - project corruption may occur if mistakes are made.
1. Change the filename of the default/front page in your web.
2. Go to your KSW project's location and open project.xml in Notepad.
3. Go to <ProjectConfiguration> -> <Definition> -> <HomePagePath> and change the old filename to the new one.
4. 'Save As' in Notepad, with all defaults but make sure Encoding is UTF-8.
Note. If you used a different text editor, it is important that it can save as 'UTF-8 with BOM' (which Notepad does).
5. Load project in KSW. Check report for 'Excluded items new: 1' and 'Excluded items removed: 1'. Open project, do nothing, save project.
6. Publish.
See also Invalid Filenames.