So I’m developing a web postal* game client which is loaded from a Linux server as a Flutter web app. When I run it on the Linux box from Chromium, no problems, it loads a binary file ok. When I try to run it from a networked Windows box, the binary file fails to load. It’s loaded by calling a PHP endpoint, passing the path of the file to a PHP script.

It was my fault. Because the game client is loaded from the Linux server and the path is a Linux path to the binary file, I’d missed that it runs on the Windows box (where the browser launches from). I’d used Platform.isLinux and Platform.Windows calls to figure out the path when I initially tested it on a Windows box.  The path to the binary file was being sent as if the file was on the Windows box because the Flutter app runs as JavaScript in the browser there. D’oh!

*Postal means a game where the game client sends orders to the server. Those are processed once an hour and the results file is picked up when the client next runs. It’s how games used to be played through the post back 30 or 40 years ago hence the name.