Running with 1.20 Minecraft, 1.19.4 Intermidiary Mappings, and LWJGL 3 3.3.1, no mods for now. With Quilt loader disabled, 1.20 loads with no problems, successful log here.
With Quilt Loader enabled, Minecraft is unable to start. This behaviour is the same for version 0.18.10 and the newest beta release 0.19.0-beta.18, link is to the full 0.19.0 log. The error is the same in both logs, they look basically the same.
The relevant error which causes the process to exit with code 2 is:
Exception caught from launcher
java.lang.RuntimeException: Unfixable conflicts
at net.fabricmc.tinyremapper.TinyRemapper.handleConflicts(TinyRemapper.java:864)
at net.fabricmc.tinyremapper.TinyRemapper.propagate(TinyRemapper.java:764)
at net.fabricmc.tinyremapper.TinyRemapper.mrjRefresh(TinyRemapper.java:1043)
at net.fabricmc.tinyremapper.TinyRemapper.apply(TinyRemapper.java:895)
at org.quiltmc.loader.impl.game.GameProviderHelper.deobfuscate0(GameProviderHelper.java:313)
at org.quiltmc.loader.impl.game.GameProviderHelper.deobfuscate(GameProviderHelper.java:247)
at org.quiltmc.loader.impl.game.minecraft.MinecraftGameProvider.initialize(MinecraftGameProvider.java:383)
at org.quiltmc.loader.impl.launch.knot.Knot.init(Knot.java:141)
at org.quiltmc.loader.impl.launch.knot.Knot.launch(Knot.java:76)
at org.quiltmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:28)
at org.prismlauncher.launcher.impl.StandardLauncher.launch(StandardLauncher.java:88)
at org.prismlauncher.EntryPoint.listen(EntryPoint.java:126)
at org.prismlauncher.EntryPoint.main(EntryPoint.java:71)
Exiting with ERROR
[21:19:17] [INFO] [Quilt Loader/GameProvider]: Loading Minecraft 1.20 with Quilt Loader 0.18.10
[21:19:17] [INFO] [Quilt Loader/Mappings]: Loading mappings: jar:file:/home/dranion/.local/share/PrismLauncher/libraries/net/fabricmc/intermediary/1.19.4/intermediary-1.19.4.jar!/mappings/mappings.tiny
[21:19:17] [WARN] [Quilt Loader/GameRemap]: Incomplete remapped file found! This means that the remapping process failed on the previous launch. If this persists, make sure to let us at Quilt know!
[21:19:17] [INFO] [Quilt Loader/GameRemap]: Preparing JARs on first launch, this may take a few seconds...
The note about the incomplete remapping did not occur on the first failure. Not sure how to troubleshoot further beyond this point, I’m new to minecraft modding in general.
The behaviour is also the same with only the Quilted Fabric API mod enabled, version 7.0.0+0.83.0-1.20