Compatibility-breaking changes between 1.16 and 1.17/1.18

[Ravana]

.png is not redirected either, so if using same way it wont be compatibility breaking.

$ filesystem.have_asset("images","maps/titlescreen.png")
false
$ filesystem.have_asset("images","maps/titlescreen.webp")
true

[octalot]

Although it isn't redirected for have_asset, .png is redirected when it gets to src/picture.cpp's load_image_file(const image::locator&).

[Ravana]

So it is only visual difference not compatibility.

[white_haired_uncle]

https://wiki.wesnoth.org/ModificationWML:

require_modification: a boolean value; if set to yes, all players have to have this modification installed to join the game. Default no in older versions and yes since 1.18.

I don't know if this is "Compatibility-breaking", but it's probably worth a note here either way.

[Pentarctagon]

Added.