When you export the game, there is an option
Convert text scenes to binary on export. If it's turned on,
.tscn files are changed to
It seems most paths in scenes/scripts/resources are substituted, but if you have a bit of code that builds the path from parts, it can slip through the cracks.
This is how i handled it in my project.
const SCENETYPE = ['tscn.converted.scn', 'scn', 'tscn']
func load_scene_instance(name, dir=''):
var file = File.new()
var path = ''
var scene = null
for ext in SCENETYPE:
path = 'res://%s%s.%s' % [dir, name, ext]
scene = load(path).instance()