Haxe no longer abuses stderr and outputs to stdout, see HaxeFoundation/haxe@f6da2aa. Without this fix, this leads the the following compiler error: >Error: Lime 5.8.2 is not compatible with Haxe 1 (version 3.2.0 or higher is required) The fix is basically the same approach vshaxe takes for backwards compatibility: vshaxe/haxe-languageserver@e119a7e